US 3853261 A
A carton, formed from a blank of paperboard or the like coated with a barrier film, is provided with a tear strip opening feature which includes a tab formed in the manufacturer's flap of the carton to facilitate opening thereof.
Description (OCR text may contain errors)
United States Patent 11 1 Moore [451 Dec. 10, 1974  Inventor:
[ CARTON WITH EASY OPENING FEATURE AND BLANK THEREFOR Norman H. Moore, Palo Alto, Calif.
 Assignee: Fibreboard Corporation, San
 Filed: Mar. 15, I973  Appl. No: 341,330
 US. Cl 229/51 AS, 229/51 TS 511 int. Cl B65d 17/20, 865d 5/74 58 Field of Search 229/51 "rs, 51 AS, 37 R  References Cited UNITED STATES PATENTS 9/1968 Foster et a1. .L 229/37 R 3,539,093 11/1970 Massengill 229/51 TS 3,761,012 9/1973 Rosenburg, Jr. 229/5-1 TS FOREIGN PATENTS OR APPLICATIONS 649,764 12/1962 Italy 229/51 AS 672,175 10/1963 Canada 1. 229/51 TS Primary Examiner-Wi1liam 1. Price Assistant Examiner-Bruce H. Bernstein Attorney, Agent, or Firm-Robert A. Beck  ABSTRACT A carton, formed from a blank of paperboard or the like coated with a barrier film, is provided'with a' tear strip opening feature which includes a tab formed in the manufacturers flap of the carton to facilitate opening thereof.
6 Claims, 4 Drawing Fignres PATENTEB 559 I w" SHEET 2 [IF 2 CARTON WITH EASY OPENING FEATURE AND BLANK THEREFOR BACKGROUND OF THE INVENTION A relatively recent development in the packaging art has been the formation of cartons from blanks coated on at least one surface with a heat sealable barrier film such as polyethylene or the like. Cartons formed from such blanks have two substantial advantages over conventional blanks. First, the heat sealing properties of the barrier film permit the carton closures to be sealed without the use of additional adhesives and second, the barrier properties eliminate the need for carton overwraps or product bags within the carton which were previously required for products which must be protected from air, moisture, vapor and the like. Unfortunately, such cartons also have one unfavorable feature; these barrier films are tough and very difficult to tear causing problems in opening the cartons. The most difficult problem is to provide means to initiate opening of a tear feature.
PRIOR ART Tear strip openers forcartons have been known and used for many years. A conventional tear strip is shown in US. Pat. No. 2,2l 8,509. This strip is formed by lines of perforations extending through the carton material and a cut line to initiate tear. Obviously, such a tear strip would destroy the barrier properties of a barrier film and permit air and moisture to reach-the product in the carton. An effort to solve the problems associated with opening such a carton is disclosed in US. Pat. No. 3,399,820, assigned to the assignee of this invention. This patent discloses a tear strip opening means formed of limited depth cuts on the interior surface of the carton and similar cuts intheexterior surface of the carton, the latter cutsspaced from the former to preserve barrier properties. A tab, shown at 15d in FIGS.
1 and 2 of the drawings of this patent, is formed on the faces of panel 15 and manufacturer's flap 11 it was found that in most instances the tab 15d was also sealed to the manufacturersjoint. Since the bond formed by these heat sealable coatings is very strong, it was extremely difficult to start the tear strip and open the carton.
SUMMARY OF THE INVENTION An object of this invention is to overcome the above, briefly described problems involved in opening a carton formed from a blank coated with a heat sealable barrier film by providing tear strip opening means which do not destroy the barrier properties of the film but which can be opened easily, and particularly to provide means whereby the tearing of such a tear strip may be easily started.
In the preferred embodiment the carton comprises a first side panel, a front panel, a second side panel, a back panel and a manufacturers flap integrally joined to an edge of the back panel and sealed to the first side panel to form a tubular carton body. Top and bottom closure flaps are suitably connected to these panels. The carton is coated with a barrier film of polyethylene or the like on both interior and exterior surfaces. A tear strip extends across three of the panels, commencing at the juncture of the manufacturers flap and the first side panel. The tear strip is formed by limited depth cuts in the interior and exterior surfaces of the carton suitably spaced to preserve the barrier properties of the carton. Limited depth cuts are also formed in the exterior surface of the carton blank in the area under the tear strip so that, when the flat folded carton is squared up into tubular form, a slight tearing occurs and a tab in the manufacturers flap is created which protrudes slightly from the carton body. This tab may then be grasped to initiate tearing of the tear strip without the necessity of tearing through the tough barrier film.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects of this invention will become apparent from the following description and accompanying drawings wherein FIG. 1 is a plan view of the outer surface of a paperboard blank adapted to be erected into a carton embodying the invention;
FIG, 2 is a perspective view of a carton formed from the FIG. 1 blank;
FIG. 3 is a view similar to FIG. 2 in which the tear strip has been partially removed; and
FIG. 4 is an enlarged cross sectional view taken along line 44 of FIG. 2 looking in the direction of the arrows.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT adapted to form top and bottom closures for the carton.
A tear strip 23 extends from the free edge of first side panel 10 across said first side panel, front panel 11 and second side panel 12, ending at scoreline 16. The tear strip comprises two spaced, limited depth parallel cut lines 24, 25, in the outer surface of the blank extending through the barrier film but not through the paperboard. At the ends of these cut lines adjacent scoreline 16,.they are joined by an angled cut line 26, also extending through the barrier film but not through the paperboard. The tear strip 23 further comprises parallel, limited depth cut lines 27,28 on the inner surface of the blank also extending through-the interior barrier film but not through the paperboard. These cut lines 27, 28 are spaced inwardly from, but parallel to, cut
' lines 23, 24. This spacing preserves a major portion of the barrier properties of the film on the carton surfaces, in that air or moisture entering a cut line must pass through the paperboard for a substantial distance to enter the sealed carton. It should be understood that a single cut line on the interior surface of the carton will serve the same purpose as the two cut lines 27, 28 although two such lines are preferred. A starting end 29, of the tear strip is formed adjacent the edge of first side panel 10. 7
Further, a tab 30, is formed in manufacturers flap 17 in the area underlying the end of tear strip 23 in the formed carton. The function of this tab will be described hereinafter in conjunction with a description of the opening of the sealed carton. The tab comprises two parallel, limited depth cut lines 31, 32 extending transversely of the manufacturers flap and located, in the final sealed carton, so that they will lie closely adjacent to, but slightly inwardly of tear strip cut lines 24, 25. These cut lines 31, 32, extend'across manufacturers flap 17 from its free edge through scoreline l8, and also extend through the barrier film but not through the paperboard. A third cut line 33, joins the ends of cut lines 31 and 32. Preferably, this cut line 33 lies slightly across scoreline 18 from manufacturer's flap 18; that is, within the area of back panel 13. This cut line 33 also extends through the barrier film but not through the paperboard.
In addition, scoreline 34 is formed across back panel 13 corresponding to the centerline of tear strip 23.
To form the carton, back panel 13 and manufacturers flap 17 are folded along scoreline 16 to lie against the inside surface of second side panel 12 and front panel 11. Then first side panel is folded inwardly so that its edge area overlies manufacturers flap 17. Heat is then applied in this area sealing the exterior of manufacturers flap 17 to the interior of first end panel 10 by means of the heat sealable barrier film to form a flat folded tubular carton.
The fiat folded carton may then be erected by first folding along scorelines and 18 to form an open tube, folding bottom'flaps 20 along scoreline 22 and heat sealing to form a bottom closure, inserting the contents and then folding top flaps 19 along scoreline 21 and heat sealing to form a top closure. This results in the completed carton shown in FIG. 2.
An interesting phenomenon occurs when the carton is opened into tubular form by folding along scorelines 15 and 18. As scoreline 18 is folded through a 90 arc, the natural stiffness of the exterior barrier film layer combined with the relative susceptibility of the underlying paperboard to tearing action causes a slight tear to-be created in the area underlying the edge of tab 30. This results in the lifting of the end of tab slightly away from the body of the carton-as shown in FIG. 2, providing a space for insertion ofa fingernail or the like to initiate removal of the tear stripfl'he tearing effect described and the formation of tab 30.is shown more clearly in F164 Folding of panel 13 and manufacturers flap 17 perpendicular position causes the area adjacent cut line 33 to tear along are 35. The end of tab 30 remains. attached to tear strip 23 as shown and protrudes outwardly from the carton body.
FIG. 3 shows the carton with the tear strip partially removed. To thus open' the carton, a fingernail or the like is inserted under tab 30 in the space formed at cut line 33. A slight force exerted outwardly on tab 30 will cause the fibers of the paperboard body to split apart across manufacturer's flap 17 in the area between cut lines 31 and 32 and between the layers of barrier film.
the paperboard fibers in the areas between exterior cut lines 24, 25 and interior cut lines 27, 28. It should be noted that tab 30 remains sealed to tear strip 23 and the entire tear strip and tab may be removed without the necessity of tearing across the tough barrier film. This may be accomplished despite the fact that the arrangement of limited depth cut lines preserves the barrier properties of the carton until it is opened. After removal of the tear strip 23, the top of the carton may be folded back along scoreline 34 to remove the contents.
This type of opening feature is particularly suitable to cartons coated with tough barrier films of material which is difficult to tear. Examples of such films are polypropylene and polyvinylidene chloride in addition to the aforementioned polyethylene. This opening feature might also be applicable to a non-barrier carton in which the glue used in sealing the manufacturers flap to the adjacent panel is very strong and difficult to separate.
It should be understood that the limited depth cut lines hereinbefore referred to should extend through the barrier film where such films are used and may extend up to about half way through the paperboard forming the carton.
What is claimed is:
l. A paperboard carton comprising a first side panel, a front panel, a second side panel and a back panel hingedly connected along parallel scorelines, a manufacturers flap hinged along a scoreline to said back panel and sealed to said first side panel to form a tubular carton body, end closure flaps hinged to said panels and adapted to form end closures for said carton,
a tear strip formed acrossat least three of said panels, said tear strip having an end at which tear is.initi-' ated, said end lying at an edge of said first side panel and sealed to said manufacturers flap therewith, and i limited depth transverse cuts formed in the area of said manufacturers flap which underlies said end of said tear strip, said transverse cuts extending across said manufacturers flap and beyond the back panel, and a longitudinal limited depth cut in said back panel joining the ends of said transverse cuts, said cuts forming tab means which protrude from the carton body when the carton is in erected condition, so that said tab means may be grasped and pulled to initiate removal of said tear strip.
- 2. The carton of claim 1 wherein'at least the exterior surface of said carton is coated with a heat sealable barrier film.
3. The carton of claim 2 wherein said heat sealable barrier film is polyethylene.
4. Thecarton of claim 2 wherein said tear strip further comprises two parallel, limited depth cut lines in the outer surface of said carton, said outlines extending through the barrier film but not through the paperboard and at least one limited depth cut line in the inte-- rior surface of saidcarton, parallel to and lying between said aformentioned cut lines.
5. A paperboard carton blank comprising a first side; panel, a front panel, a second side panel, a back panel and a manufacturers flap hingedly connected along scorelines, said manufacturer's flap having a free edge, and said first side panel having a free edge, and end 010-, sure flaps hinged along scorelines to the said panels,
said manufacturers flap adapted to be sealed to said first side panel to form a tubular carton body,
a tear strip extendingacross said side panels and said front panel and having an end at the edge of said first side panel adapted to be sealed to said manufacturers flap,
said tear strip comprising two parallel, limited depth cut lines in the exterior surface of said blank and at least one limited depth cut line in the interior surface thereof, parallel to and lying between said 10 surface of the blank is coated with a heat sealable barfirst mentioned cut lines,
and tab means formed in the area of said'manufacturers flap underyling and sealed to said end of said tear strip, said tab means adapted to protrude from rier film, and said cut linesin said exterior surface and said cuts extend through said barrier film but not through said paperboard.