US3727750A

US3727750A - Sterile package and blank therefor

Info

Publication number: US3727750A
Application number: US00210051A
Authority: US
Inventors: N Petter
Original assignee: STANDARD PAPER BOX CORP
Current assignee: STANDARD PAPER BOX CORP
Priority date: 1971-12-20
Filing date: 1971-12-20
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17

Abstract

A sterile package formed from a blank made of a delaminatable material, preferably paperboard, has a tear strip defined therein by scoring the blank to define a plane of cleavage along which the tear strip delaminates. An inwardly folded tab is formed on one end of the tear strip for bonding to the package to form a bacteria tight seal at the end of the tear strip. The tab is pulled to open the package by delaminating the tear strip along its plane of cleavage.

Description

United States Patent [1 1 Petter 1 Apr. 17, 1973 STERILE PACKAGE BLANK THEREFOR [75] Inventor: Noel A. Petter, Glendale, Calif.

[73] Assignee: Standard Paper Box Corp., Los Angeles, Calif.

[22] Filed: Dec. 20, 1971 W3 [21] Appl. No.2 210,051

[52] [1.5. CI ..206/63.2 R, 229/51 TS [51] Int. Cl ..A61b 19/02, A611 15/00, 865d 5/54 [58] Field of Search ..206/46 SG, 46 ST,

206/56 AA, 63.2 R; 229/51 DB, 51 AS, 51 TS, 51 TC, 51 SC, 51 WE; 220/54 [56] References Cited UNITED STATES PATENTS 2,777,601 1/1957 Cheeley a ..220/54 3,043,472 7/1962 Nemoede ..229/51 TS UX 3,263,900 8/1966 Link et a1 ..229/51 TS 3,498,448 3/1970 Kuster ..229/51 TS X 3,502,257 3/1970 3,526,353 9/1970 Jaeschke ..229/51 TS 3,561,669 2/1971 Postweiler et al ..229/51 TS 3,595,466 7/1971 Rosenburg, Jr... ...229/51 TC X 3,638,853 2/1972 Perry .229/5l TS Primary Examiner-Samuel B. Rothberg Assistant Examiner-Steven E. Lipman Attorney-Herbert A. Huebner et al.

[ ABSTRACT A sterile package formed from a blank made of a delaminatable material, preferably paperboard, has a tear strip defined therein by scoring the blank to define a plane of cleavage along which the tear strip delaminates. An inwardly folded tab is formed on one end of the tear strip for bonding to the package to form a bacteria tight seal at the end of the tear strip, The tab is pulled to open the package by delaminating the tear strip along its planeof cleavage.

15 Claims, 8 Drawing Figures PATENTED APR 1 7 I973 SHEET 2 [1F 2 STERILE PACKAGE AND BLANK THEREFOR BACKGROUND OF THE INVENTION The present invention relates to instrument packages and more particularly to an improved package for sterile instruments or commodities.

Instruments and devices employed in surgery and many other medical procedures need to be sterilized and maintained bacteria free until used in order to prevent infections. Accordingly, such instruments are generally sterilized and stored in packages made of a bacteria impervious material. Such packages are generally made of a delaminatable material, like paperboard, through which a selected gas may be passed to sterilize the instruments in the packages after they have been sealed.

Such sterile packages must be designed for opening in a rapid sterile manner so that during surgery, for example, an instrument may be rapidly removed from its sterile package without contaminating it.

Heretofore, tear strip arrangements have been devised for opening sterile packages made of delaminatable materials like paperboard. The tear strips have generally been formed by scoring the exterior and interior surfaces of the paperboard to define planes of cleavage therein along which the tear strips delaminate and the packages were opened by gripping one end of the tear strips and pulling. In order to insure that these packages were bacteria impervious, the tear strip ends which were pulled upon to open the packages generally had to be adhesively bonded to the packages to form bacteria tight seals therewith.

Due to the fact that the tear strip ends which were pulled upon were adhesively bonded to the packages, these tear strip arrangements frequently malfunctioned, delaminating too high along planes other than the defined cleavage planes. This improper delamination was caused due to the fact that the adhesive bonds between the tear strip ends and the packages were stronger than the bond between the plies of delaminatable paperboard material from which the packages were made.

The frequent malfunctioning of the prior art tear strip arrangements constituted a significant drawback to thev use of the prior art sterile packages since if the tear strips delaminated too high a layer of paper would be left in the region of the packages from which the tear strips had been removed. As a consequence, the packages would not be properly opened and the sterile instruments could not be easily removed from the sterile packages without running the risk of contaminating them.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide an improved sterile package and blank therefor which may be quickly and easily opened without malfunction so that the sterile contents of the package may be removed therefrom without being contaminated.

It is another object of the present invention to provide an improved sterile package and blank therefor having a tear strip with an integral folded over tab formed on one end of the tear strip, the tab being for bonding to the package to form a bacteria tight seal therewith and for pulling upon to remove the tear strip to open the package.

In accomplishing these and other objects, there is provided in accordance with the present invention a sterile package or container made at least in part of a delaminatable material, preferably paperboard. The sterile package is made from a folded blank and has a removable tear strip formed in the delaminatable material by scoring the exterior and interior surfaces of the blank so as to define a plane of cleavage along which the tear strip may be delaminated to open the container. An inwardly folded tab is formed preferably integral with the tear strip on one end thereof and the exterior surface of the folded tab is bonded to the package to make a bacteria tight seal therewith. The sterile package may be opened by pulling on the tab to remove the tear strip and the end portion of the tear strip overlapping and adjacent to the folded tab automatically delaminates along the proper plane of cleavage since there is no adhesive bond between this end portion of the tear strip and the sterile package. Any malfunction of the tear strip is prevented by the glue lap formed by the folded over tab and is terminated at the edge of this glue lap.

Additional objects of the present invention reside in the specific construction of the exemplary sterile package and the blank from which it is formed which are hereinafter particularly described in the specification and shown in the several drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut-away perspective view of a portion of a sterile package according to the present invention;

FIG. 2 is a perspective view as in FIG. 1 illustrating the tear strip being removed from the sterile package;

FIG. 3 is an exploded perspective view of the sterile package of FIG. 1 illustrating the tear strip separated therefrom with the sterile package severed into two portions;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 2;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 1; 7

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 2; and

FIG. 8 is a partially cut-away plan view of the exterior surface of a blank which may be folded to form the sterile package of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in more detail, there is shown in FIG. 1 a sterile package or container generally identified by the numeral 10. The container 10 preferably is a substantially rectangular box structure having side walls 11-14 and end walls 15, one of which is shown, and is formed from a blank 16. The blank 16, which is shown in FIG. 8, is made of a suitable delaminatable material, such as paperboard, and has an exterior and interior surface. The exterior surface of the blank 16 is shown in FIG. 8 and the interior surface of the blank is defined as its other side. The blank 16 shown in FIG. 8 is cut and scored for forming the rectangular box structure 10.

The blank 16 preferably has longitudinal extending

edge portions

17 and 18 which are adhesively bonded together as glue laps to seal the longitudinal dimension of the box closed, as shown in FIG. 1. The

box edge portions

17 and 18 are formed by forming fold or

crease lines

19 and 20, respectively, in the box blank 16. The

crease lines

19 and 20 are preferably mutually parallel and the

box edge portions

17 and 18 are foldable inwardly along these crease lines like flaps. The

crease lines

19 and 20 are also preferably parallel to the

outside edges

21 and 22, respectively, of the

blank edge portions

17 and 18.

A tear strip 25 having

ends

26 and 27 with a tab 28 formed on one end thereof is defined in the side walls 11-14 of the package 10 to extend entirely around the package circumference. The tear strip 25, its

ends

26, 27 and the tab 28 are defined in the package 10 by cutting pairs of

score lines

29 and 30 in the blank 16, as shown in FIG. 8, thereby to form a plane of cleavage along which the tear strip delaminates as is hereinafter explained.

The score lines 29 are cut in the interior surface of the blank 16, are preferably mutually parallel, and are cut to extend from one longitudinal blank edge 21 to its other edge 22. The score lines 29 preferably extend substantially perpendicular to the

blank edges

21 and 22 so that the tear strip 25 lies perpendicular to the longitudinal dimension of the box 10.

The score lines 30 are cut in the exterior surface of the blank 16 and extend parallel to the score lines 29 .from the blank edge 21 to points 31 on the blank 16.

The score lines 30 lie outside of the score lines 29 in the region on the blank 16 between the edge 21 and the points 31. From the points 31, the score lines 30 are cut in the exterior surface of the blank 16 to taper towards each other along straight lines to the blank edge 22. The tapering score lines 30 are preferably cut to intersect the blank fold line 20 at the points of intersection 32 of the score lines 29 therewith. Thereby, the portion of the score lines 30 between the

points

31 and 32 lie outside of the score lines 29 while the portion of the score lines 30 between the points 32 and the blank edge 22 lie within the score lines 29.

As before-mentioned, the tear strip 25 has

ends

26 and 27 and a tab 28 formed on one end thereof. As shown in FIG. 8, the tab 28 is that portion of the blank 16 defined by the

score lines

29 and 30 which lies between the fold line 20 and the blank edge 22. The tab 28 is an integral part of the tear strip 25 and is joined with the tip of the tear strip end 27 at the fold line 20. The tear strip end 27 is that portion of the tear strip defined by the

score lines

29 and 30 which lies between the crease 20 and the points 31 on the blank. The tear strip end 26 is the portion of the tear strip 25 defined by the

score lines

29 and 30 between the blank edge 21 and the fold line 19.

It is noted that a pair of tapering score lines 33 interconnected by a transverse score line 34 may be cut in the exterior surface of the tear strip end 26 as illustrated. The tapering lines 33 are cut to extend from the points of intersection of the score lines 29 with the fold line 19 to taper towards each other to the blank edge 21. The score line 34 which extends transversely on the tear strip 25 is cut preferably along the fold line 19. The score lines 33 and 34 define a triangular area on the tear strip end 26 which corresponds in shape to the tapered tab 28 defined by the score lines 30. It is noted, as hereinafter explained, that the score lines 33 and 34 may not be desired or necessary in all cases.

The sterile package 10 may be constructed by folding the blank 16 and sealing it along its edges, thereby to form a bateria impervious enclosure. When folded into the sterile package 10, the interior surface of the blank edge portion 18 is folded inwardly against the interior surface of the package wall 14 and the exterior surfaces of the

edge portions

17 and 18 are bonded together, preferably by use of a suitable adhesive, in a double layer glue lap arrangement to form a bacteria tight seal.

The exterior surfaces of the

edge portions

17 and 18 are bonded together with the score lines 30 defining the tab 28 aligned with the tapering score lines 33 on the tear strip end 26. It is noted that the width of the edge portion 18 is preferably slightly larger than the width of the edge portion 17 so that the folded over tab 28 defined on edge portion 18 extends slightly beyond the package wall 11, as shown in FIG. 1, when the

edge portions

17 and 18 are bonded together with their

edges

21 and 22 aligned.

In the sterile container 10, the tear strip ends 26 and 27 overlap each other and are separated by the inwardly folded tab 28. In order to remove the tear strip 25 from the package 10, the portion of the tab 28 which extends beyond the box wall 11 is gripped and pulled away from the box 10.

Pulling on the tab 28 causes the bacteria tight seal between the exterior surface of the tab 28 and the triangular area defined by the score lines 33 and 34 on the tear strip end 26 to be broken. The seal is broken by delamination occurring within the tab 28 along the plane of cleavage defined by the depth of the score lines 29 and 30. It is noted that the score lines 33 and 34 on the tear strip end 26 function to aid and facilitate the delamination of the tab 28 from the box 10 when the bacterial tight seal is broken. The tapered shape of tab 28 makes it easier to delaminate the tab 28 towards its tip. As shown in FIGS. 2 and 3, the tab 28 delaminates leaving exposed the

delaminated surfaces

40 and 41 on the tear strip end 26 and tab 28, respectively. It is further noted that the score lines 33 and 34 may not be necessary in all cases and that while the tapered cut of the tab 28 is preferred other shapes of tabs could be employed. Preferably, however, the tab 28 is appropriately shaped so that no lateral delamination is necessary to delaminate it from the box 10. Any such lateral delamination would increase theforce necessary to delaminate the tab 28 and restrict the delaminating action.

As the tab 28 is pulled away from the box 10, as shown in FIG. 7, to break its bacteria tight seal therewith, the tab 28 guides the delamination of the end 27 of the tear strip 25 from the package 10. The tear strip 25 delaminates along the plane of cleavage defined by adjacent ones of the score lines 29 and 30, as shown in FIGS. 4 and 5, leaving exposed the

delaminated surfaces

42 and 43 on the box 10 and the tear strip 25, respectively. Since the ends of the tear strip 25 overlap, removal of the tear strip 25 from the package 10 automatically separates the package into two portions 10a and 10b, as shown in FIG. 3.

It is noted that the plane of cleavage of the tear strip is defined by the alignment of the bottoms of the

adjacent score lines

29 and 30, and that preferably each of the score lines hereinbefore described are cut to a depth of approximately one-half of the thickness of the paperboard blank 16. It is further noted that since the bacteria tight seal at the end 27 the tear strip is made by bonding the tab 28 as a glue lap to the package 10 that no adhesive bond is necessary between the strip end 27 and the package 10 in order to seal the package 10 closed. As a consequence, the tear strip does not have the tendency to malfunction by delaminating too high but rather readily delaminates along the plane of cleavage defined by the score lines 29 and 30. Additionally, since the delamination of the tab 28 to break the bacteria seal with the package 10 is a separate delaminating action distinct from the delamination of the tear strip 25, any delamination of the tab 28 along a plane other than the cleavage plane defined by the

score line

29 and 30 will have no detrimental effect on the delamination of the tear strip 25 from the package 10 and further any improper delamination of the tab 28 is terminated at the edge of the glue lap it forms.

Once the tear strip 25 has been completely removed, as shown in FIG. 3, a sterile instrument enclosed in the package 10 may be readily removed therefrom by merely tilting the package portion 10b so that the instrument slides from the package onto an appropriate sterile surface, such as a sterile surgical tray. With the tear strip 25 removed and the box severed into the portions 10a and 10b, there is no danger of contaminating the sterile instrument since all edge surfaces of the sterile package 10 which would make contact with the sterile instrument are sterilized.

Thus there has been provided an improved sterile box having a readily removable tear strip which delaminates along a designed plane of cleavage so as to separate the sterile box into at least two portions, thereby to facilitate the removal of sterile instruments therefrom without running the risk of contaminating the sterile instruments. Further, the improved tear strip has a folded over. tab portion formed on one end which may be bonded to make a bacteria tight seal at the end of the tear strip so as to eliminate the need for an adhesive bond between the interior of the tear strip and the package.

Although I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention. For example, the folded over tab could be joined with the tear strip rather than being formed as an integral part thereof. Further, the tab could be bonded to the package to form a bacteria tight seal therewith to be detachable therefrom in a manner other than by being delaminated.

delaminates to separate from said package, said tear strip having first and second end; and

a tab formed on the first end of said tear strip, said tab being folded inwardly with its interior surface folded toward the interior surface of the first end of said tear strip and having its exterior surface bonded to said package to make a bacteria tight seal therewith whereby to open said package said tab is pulled away from said package to break its bond with said package and delaminate said tear strip along said plane of cleavage.

2. The invention defined in claim I, wherein:

the portion of said structure made from said delaminatable material extends around the entire circumference of said package and overlaps to a predetermined extent;

said tear strip is defined by said scorelines to extend around the entire circumference of said structure and the ends of said tear strip are defined by said score lines to overlap each other so that removal of said tear strip from said structure separates said package into two portions; and

the exterior surface of said tab is bonded to the exterior surface of the second end of said rear strip to make a bacteria tight seal therewith.

3. The invention defined in claim 2, wherein said tear strip is defined by a first and second pair of spaced apart score lines, said first pair of score lines being cut a predetermined distance into the interior surface of said delaminatable material to extend from the tip of the first end of said tear strip to the tip of the second end of said tear strip, said second pair of score lines being cut a predetermined distance into the exterior surface of said delaminatable material to extend from the points of intersection of said first score lines with the tip of the first end of said tear strip outside of said first score lines to the tip of the second end of said tear strip whereby the adjacent ones of said first and second score lines cooperate with each other to form said cleavage plane along which said material delaminates.

4. The invention defined in claim 3-, wherein:

said first pair of score lines are mutually parallel;

the portion of said second pair of score lines extending from the tip of the second end of said tear strip to the first end of said tear strip are parallel with said first score lines; and

the portion of said second pair of score lines extending along the first end of said tear strip to the tip thereof taper towards each other to intersect said first end tip at the points of intersection of said first score lines therewith.

5. The invention defined in claim 4, wherein said tab is integral with said tear strip being also formed from said delaminatable material and extends from the tip of said first tear strip end.

6. The invention defined in claim 5, wherein said tab is defined by extending said first pair of mutually parallel score lines along the interior surface thereof to its tip and by'extending the tapering portion of said second pair of score lines along the exterior surface thereof to its tip so that the portion of said second score lines cut in said tab lie within said first score lines and the adjacent ones of said first and second score lines cooperate with each other on said tab to form a plane of cleavage for said tab along which said tab delaminates when pulled away from said package.

7. The invention defined in claim 6, wherein:

the tapering portion of said second pair of score lines are straight lines so that said second score lines define a triangular area on the exterior surface of said tab; and including:

a third pair of score lines cut in the exterior surface of the second end of said tear strip to define a triangular area therein corresponding in shape to the triangular area defined in said tab, the triangular area defined by said third score lines being positioned on said second tear strip end to be in alignment with and bonded to the triangular area of said tab whereby said second score lines on said tab are aligned with said third score lines on said second tear strip end to facilitate the delamination of said tab when pulled away from said package.

8. The invention defined in claim 7, wherein:

said third score lines extend to the tip of the second endof said tear strip; and including:

a transverse score line interconnecting the ends of said third score lines remote from the tip of the second end of said tear strip.

9. The invention defined in claim 8, wherein:

said structure forming the bacteria impervious enclosure is made of a delaminatable paperboard material;

each of said score lines are cut to a depth of approximately one half the thickness of said paperboard material; and

said tab is adhesively bonded to the second end of said tear strip.

10. The invention defined in claim 9, wherein the portion of said tab which joins the tip of the first end of said tear strip extends outward from said structure forming the bacteria impervious enclosure so that said tab may be easily gripped for pulling thereon.

11. In a sterile package made at least in part of a paperboard material which has a removable tear strip formed in said paperboard material by scoring the exterior and interior surfaces of said paperboard material to define a plane of cleavage therein along which said tear strip delaminates to open said package, the improvement of a tab formed integral with one end of said tear strip, said tab being folded inwardly with its interior surface folded toward the interior surface of said tear strip and having its exterior surface adhesively bonded to said package in a bacteria tight seal therewith whereby to open said package so that a sterile commodity may be removed therefrom said tab is pulled away from said package to break its adhesive bond therewith and delaminate said tear strip along said plane of cleavage.

12. The invention defined in claim 11, wherein said tab tapers narrowing towards its tip.

13. A blank made of a bacteria impervious paperboard which is cut, scored and creased to be foldable to form a bacteria impervious enclosure when adhesively sealed along its edges, said paperboard blank having an exterior and interior surface and comprising:

first and second edge portions the exterior surfaces of which are adhesively secured together when said paperboard blank is folded to form a bacteria impervious enclosure, said second edge portion being foldable inwardly so that the exterior surface of said second edge portion may be adhesively secured to the exterior surface of said first edge portion; and a tear strip defined by scoring the exterior and interior surfaces of said paperboard blank from the outside edge of said first edge portion to the line along which said second edge portion folds inwardly to define a plane of cleavage therein along which said tear strip delaminates to separate from said blank; tab for pulling said tear strip from said blank defined in said second edge portion by continuing said score lines across the exterior and interior surfaces of said blank to the outside edge of said second edge portion, said tear strip and tab are defined by a first and second pair of spaced apart score lines, said first pair of score lines being cut into the interior surface of said blank to extend from the outside edge of said first edge portion to the outside edge of said second edge portion, said second pair of score lines being cut into the exterior surface of said blank to extend from the points of intersection of said first score lines with the line along which said second edge portion folds in one direction to the outside edge of said first edge portion and in the other direction to the outside edge of said second edge portion, said second score lines lying outside of said first score lines in the region between the outside edge of said first edge portion and the line along which said second edge portion folds, said second score lines lying inside of said first score lines in the region between the line along which said second edge portion folds and the outside edge of said second edge portion.

14. The invention defined in claim 13, wherein:

the portion of said first score lines lying between the line along which said second edge portion folds and the outside edge of said second edge portion are mutually parallel; and

the portion of said second score lines lying between the line along which said second edge portion folds and the outside edge of said second edge portion taper towards each other along straight lines so that said tab is defined on the exterior surface of said second edge portion as a triangular area.

15. The invention defined in claim 14, including score linescut in the exterior surface of said first edge portion to define a triangular area therein which is positioned to be in alignment with said triangular tab area whenever said blank is folded to form a bacteria impervious enclosure, the triangular area defined on the exterior surface of said first edge portion corresponding in shape to said triangular tab area.

Claims

1. A sterile package, comprising: structure forming a bacteria impervious enclosure for a sterile instrument, said structure being made at least in part from a delaminatable material; a tear strip for opening said package defined in said delaminatable material by scoring the exterior and interior surfaces of said material to define a plane of cleavage therein along which said tear strip delaminates to separate from said package, said tear strip having first and second end; and a tab formed on the first end of said tear strip, said tab being folded inwardly with its interior surface folded toward the interior surface of the first end of said tear strip and having its exterior surface bonded to said package to make a bacteria tight seal therewith whereby to open said package said tab is pulled away from said package to break its bond with said package and delaminate said tear strip along said plane of cleavage.

2. The invention defined in claim 1, wherein: the portion of said structure made from said delaminatable material extends around the entire circumference of said package and overlaps to a predetermined extent; said tear strip is defined by said score lines to extend around the entire circumference of said structure and the ends of said tear strip are defined by said score lines to overlap each other so that removal of said tear strip from said structure separates said package into two portions; and the exterior surface of said tab is bonded to the exterior surface of the second end of said tear strip to make a bacteria tight seal therewith.

4. The invention defined in claim 3, wherein: said first pair of score lines are mutually parallel; the portion of said second pair of score lines extending from the tip of the second end of said tear strip to the first end of said tear strip are parallel with said first score lines; and the portion of said second pair of scoRe lines extending along the first end of said tear strip to the tip thereof taper towards each other to intersect said first end tip at the points of intersection of said first score lines therewith.

6. The invention defined in claim 5, wherein said tab is defined by extending said first pair of mutually parallel score lines along the interior surface thereof to its tip and by extending the tapering portion of said second pair of score lines along the exterior surface thereof to its tip so that the portion of said second score lines cut in said tab lie within said first score lines and the adjacent ones of said first and second score lines cooperate with each other on said tab to form a plane of cleavage for said tab along which said tab delaminates when pulled away from said package.

7. The invention defined in claim 6, wherein: the tapering portion of said second pair of score lines are straight lines so that said second score lines define a triangular area on the exterior surface of said tab; and including: a third pair of score lines cut in the exterior surface of the second end of said tear strip to define a triangular area therein corresponding in shape to the triangular area defined in said tab, the triangular area defined by said third score lines being positioned on said second tear strip end to be in alignment with and bonded to the triangular area of said tab whereby said second score lines on said tab are aligned with said third score lines on said second tear strip end to facilitate the delamination of said tab when pulled away from said package.

8. The invention defined in claim 7, wherein: said third score lines extend to the tip of the second end of said tear strip; and including: a transverse score line interconnecting the ends of said third score lines remote from the tip of the second end of said tear strip.

9. The invention defined in claim 8, wherein: said structure forming the bacteria impervious enclosure is made of a delaminatable paperboard material; each of said score lines are cut to a depth of approximately one half the thickness of said paperboard material; and said tab is adhesively bonded to the second end of said tear strip.

13. A blank made of a bacteria impervious paperboard which is cut, scored and creased to be foldable to form a bacteria impervious enclosure when adhesively sealed along its edges, said paperboard blank having an exterior and interior surface and comprising: first and second edge portions the exterior surfaces of which are adhesively secured together when said paperboard blank is folded to form a bacTeria impervious enclosure, said second edge portion being foldable inwardly so that the exterior surface of said second edge portion may be adhesively secured to the exterior surface of said first edge portion; and a tear strip defined by scoring the exterior and interior surfaces of said paperboard blank from the outside edge of said first edge portion to the line along which said second edge portion folds inwardly to define a plane of cleavage therein along which said tear strip delaminates to separate from said blank; a tab for pulling said tear strip from said blank defined in said second edge portion by continuing said score lines across the exterior and interior surfaces of said blank to the outside edge of said second edge portion, said tear strip and tab are defined by a first and second pair of spaced apart score lines, said first pair of score lines being cut into the interior surface of said blank to extend from the outside edge of said first edge portion to the outside edge of said second edge portion, said second pair of score lines being cut into the exterior surface of said blank to extend from the points of intersection of said first score lines with the line along which said second edge portion folds in one direction to the outside edge of said first edge portion and in the other direction to the outside edge of said second edge portion, said second score lines lying outside of said first score lines in the region between the outside edge of said first edge portion and the line along which said second edge portion folds, said second score lines lying inside of said first score lines in the region between the line along which said second edge portion folds and the outside edge of said second edge portion.

14. The invention defined in claim 13, wherein: the portion of said first score lines lying between the line along which said second edge portion folds and the outside edge of said second edge portion are mutually parallel; and the portion of said second score lines lying between the line along which said second edge portion folds and the outside edge of said second edge portion taper towards each other along straight lines so that said tab is defined on the exterior surface of said second edge portion as a triangular area.

15. The invention defined in claim 14, including score lines cut in the exterior surface of said first edge portion to define a triangular area therein which is positioned to be in alignment with said triangular tab area whenever said blank is folded to form a bacteria impervious enclosure, the triangular area defined on the exterior surface of said first edge portion corresponding in shape to said triangular tab area.