Paperboard carton having an audible locking sound

FIELD OF THE INVENTION

[0002] The present invention relates to paperboard cartons. Specifically, the present invention relates to paperboard cartons for containing granular materials.

BACKGROUND OF THE INVENTION

[0003] Reclosable cartonboard cartons for storing granular materials, such as powdered laundry detergents, have been available for many years. These cartons are typically formed from a cardboard which is laminated or coated with a moisture barrier material, such as polyethylene, polypropylene, varnish or other barrier materials known in the art. Because the cardboard has a natural spring back, the lids of these cartons tend to open thereby leading to contamination of the product and/or absorption of moisture by the product, both of which are undesirable. As such, the ability to repeatedly open and close/lock these cartons has long been a desirable property.

[0004] Some closure/locking systems have included various flap and tab interlocking arrangements in combination with a perforated line. In such a carton, the perforation between the locking flap and the tab is broken by a user during the peak first opening. These closure arrangements generally require highly accurate folding and gluing steps during manufacture to achieve proper alignment between the locking flap and the tab, but when the perforation is too hard to break, it may be too difficult to open the lid.

[0005] In addition, it has now been found that consumers are dissatisfied by current locking systems for the lid of a paperboard carton, as they are viewed as less secure than, for example, a plastic lid. However, employing a plastic lid adds significant raw material costs to the carton, as well as manufacturing and supplier complexities and expenses. While paperboard cartons may also employ separate paperboard lids which are glued to the main carton after the detergent is filled therein, such a separate manufacturing step and carton formation step also can significantly add expenses and complexity to a manufacturing line.

[0006] Accordingly, the need exists for a paperboard carton which is repeatably openable and closable, which is easy to open the first time and subsequent times, which has a lid which is securely closeable and/or which significantly reduces manufacturing complexity and/or expenses.

SUMMARY OF THE INVENTION

[0007] The present invention relates to an improved reclosable paperboard package for containing a granular material, including a container base and a lid formed from a single piece of paperboard. The container base includes a first panel which forms a locking mechanism with the lid. When the lid is closed, an audible locking sound is heard having a sound pressure level of at least about 78 dBSPL. The reclosable paperboard package also preferably has a peak first opening strength of less than 70 N.

[0008] It has now been found that a paperboard package may be repeatably openable and closeable and yet still provide a securely closeable package. Furthermore, it has now been found that such a package may be made from a single piece of paperboard, thereby saving significant manufacturing and raw material expenses and reducing manufacturing complexity.

[0009] All documents cited are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the invention will be better understood from the following description of the accompanying figures in which like reference numerals identify like elements, and wherein:

[0011]
FIG. 1 is a perspective view of a preferred embodiment of the reclosable paperboard package herein in the open position with the lid raised;

[0012]
FIG. 2 is a perspective view of a preferred embodiment of the reclosable paperboard package herein, prior to opening;

[0013]
FIG. 3 is a top plan view of a preferred blank suitable for making the reclosable paperboard package herein, with a close-up of a preferred opening tab;

[0014]
FIG. 4 is an enlarged partial cross-sectional side view of the package of FIG. 2, taken along line 4-4 to show a preferred locking mechanism;

[0015]
FIG. 5 is an enlarged partial cross-sectional side view of a preferred embodiment of an alternate locking mechanism; and

[0016]
FIG. 6 is a top plan view of a preferred blank suitable for making the reclosable paperboard package herein, with a close-up of a preferred opening tab.

[0017] The figures herein are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0018] As used herein, the term “comprising” means that other elements, which do not affect the end result can be added. This term encompasses the terms “consisting of” and “consisting essentially of”.

[0019] As used herein, the term “dBSPL” indicates the sound pressure level (SPL), in decibels. SPL is a single measurement of sound pressure in decibels relative to the threshold of hearing. SPL measurements are defined herein as 2×10−5 Newtons per Meter2 or 20 microPascals.

[0020] Referring to the figures, in FIG. 1, a preferred reclosable paperboard package, 10, is illustrated as a six-sided carton having a container base, 12, having a first panel, 14, a second panel, 16, and two side panels, 18. A lid, 20, is attached to the second panel, 16, by a folded hinge, 22. The folded hinge, and in fact, most corners, is preferably formed by an integral score line in the paperboard blank (see, FIG. 3, at 36), although other means known in the art may be used, such as half-cuts. The lid, 20, contains two lid side panels, 24, and a lid front panel, 26, which further contains three lock tabs, 28a, which cooperate with the three corresponding lock slot, 28b, to form three locking mechanisms, 28, distal to the folded hinge, 22. Each lock tab, 28a, preferably tapers toward its distal end, to facilitate engagement of the distal end with its corresponding lock slot, 28b. While a single locking mechanism may be sufficient in the above design, multiple lock mechanisms are preferred, as the lid is more securely held in place, and also because they increase the sound pressure level of the audible locking sound.

[0021] The side panel, 18, has a depth, α, which is less than the depth, β, of the lid side panel, 24. This difference in depth between α and β facilitates the creation of an audible locking sound when the lid is closed. For optimal sound generation, ease of use, and economy, the difference (see FIG. 4 at A) in depth between α and β is typically from about 0.5 mm to about 15 mm, preferably from about 1 mm to about 10 mm, and more preferably from about 2 mm to about 5 mm. Without intending to be limited by theory, it is believed that if this difference is too small, little audible locking sound is heard, whereas if this difference is too large, excessive paperboard is used, thereby wasting raw materials, and increasing expenses.

[0022] The first panel, 14, second panel, 16, and two side panels, 18, further define an opening, 32, through which the product, 30, may be removed from the package, 10, when the lid, 20, is in the raised position.

[0023]
FIG. 2 shows a six-sided carton having a lid, 20, interconnected with a container base, 12, first panel, 14, second panel, 16, container bottom, 34, and side panels 18. The lid, first panel, second panel and side panels each have inner and outer surfaces, wherein the inner surfaces are disposed within the interior of the package, 10, and the exterior surfaces are disposed about the exterior of the package (the exterior surfaces only being visible in FIG. 2). FIG. 2 also shows the lock tab, 28, engaged within the lock slot, 28b, to form the locking mechanism, 28. The locking mechanism, 28, keeps the lid, 20, closed to prevent spillage of the granular material, moisture absorption by the granular material, contamination of the granular material, etc.

[0024] In FIG. 3, a top plan view of a preferred blank, 36, suitable for making the reclosable paperboard package herein with a close up of a preferred opening tab, 37, is provided, specifically showing the lock tabs, 28a. The blank, 36, also indicates that the depth, β, of the lid, 20, is greater than the depth, α, of the side panel, 18. Similarly, the width, δ of the lid, 20, is greater than the width, γ, of the second panel, 16, and the first panel, 14. This, in turn, increases the sound pressure level of the locking mechanism, 28, when the lid, 20, is closed. The opening tab, 37, further facilitates the first opening of the package, 10, as it provides a breaking seal which has a relatively low peak first opening strength. The opening tab, 37, is typically affixed to the inside of the lid, 20, at a suitable location to insure a seal. The blank, 36 of FIG. 3 is viewed from the side which becomes the outside of the final reclosable paperboard package.

[0025]
FIG. 3 also indicates a plurality of half-cuts, 38, which allow the peak first opening strength to be significantly decreased. In the figures, half-cut lines are indicated by dashed and dotted lines. Additional half-cuts, 38a, are also indicated on the backside of the blank, 36. the lock tab, 28a, also is defined with a half-cut, 38, which significantly increases the flexibility of the lock tab, 28a, and volume of the audible locking sound, as compared to a mere fold. As used herein, the term “peak first opening strength” indicates the maximum or peak amount of force required to open the package, 10, the first time after sealing, by lifting the lid, 20, to break open the relevant seal(s) enough so that the lid, 20, is completely open, as seen in FIG. 1. Thus, the peak first opening strength, would be measured, for example, after a consumer purchases a package containing a granular detergent, and in preparation to use the granular detergent contained therein. After the peak first opening strength is achieved, and the package seal(s) start to break, the force required to progress to a completely open package typically decreases significantly. The half-cut, 38, herein is a cut in the paperboard which does not completely slice through the paperboard. Instead, it cuts through only a portion of the paperboard. Thus, when force is exerted on the paperboard, the paperboard itself separates between the interior and exterior surfaces of the paperboard. Such a half-cut seal therefore typically breaks open with significantly less force than, for example, a traditional glued seal which requires that the glue be pealed off of at least one surface in order to break the seal. The half-cut, 38, may be employed in conjunction with a full-cut, 39, to adjust the peak first opening strength of the package. The full-cut may also, of course, further define an opening tab, 37, a lock tab, 28a, a locking mechanism, 28, etc. The full-cut, 39, herein is a “normal” cut which slices completely through the paperboard.

[0026] Accordingly, it is preferred that the package have a peak first opening strength of less than about 70 N, preferably from about 3 N to about 60 N, and more preferably from about 5 N to about 40 N, as measured perpendicular to the lid prior to opening. Additional seals, and methods of assembling blanks into packages are described in, for example, WO 00/51897 to Hofte, published on Sep. 8, 2000.

[0027]
FIG. 4 shows a preferred locking mechanism, 28, as seen from an enlarged partial cross-sectional side view of the package of FIG. 2, taken along line 4-4. In FIG. 4, the lock tab, 28a, is seen engaged with lock slot, 28b. An adhesive portion, 40, affixes the first panel to a first panel flap, 42, which are formed by a fold, 44. In the figures, fold lines are indicated by dashed lines. In FIG. 4, the angle, θ, indicates the angle between the lid front panel, 26, and the lock tab, 28a, when the lid, 20, is closed. This angle is typically from about 5° to about 85°, preferably from about 20° to about 80°, and more preferably from about 30° to about 70°. Without intending to be limited by theory, it is believe that this angle also increases the sound pressure level of the auditory locking sound, by enhancing the locking “click” of the package when the lid is closed.

[0028] As can also be seen in FIG. 4, there exists a gap, A, between the inner surface of the lid front panel, 26, and the exterior surface of the first panel, 14, which enhances the audible locking sound made when the lid, 20, is closed and the lock tab, 28a, locks into the lock slot, 28b. For purposes of clarity, it is reiterated that this gap, A, corresponds to the difference in depth between α and β, described above. Furthermore, in FIG. 4 it can be seen that the lock slot, 28b, has a depth, B, which is preferably from about 0.2 mm to about 5 mm, preferably from about 0.5 mm to about 3.5 mm, and more preferably from about 0.7 mm to about 2 mm, for use with a lock tab formed from a paperboard having a thickness of about 0.7 mm to 1 mm. For packages where the lock tab is formed from a thicker paperboard, this lock slot depth, B, may be correspondingly larger. Such a depth helps to ensure that the locking mechanism stays locked and that the lock tab, 28a, seldom unintentionally slips out of the lock slot, 28b.

[0029] In FIG. 5, an enlarged partial cross-sectional side view of a preferred embodiment of an alternate locking mechanism is provided which is formed by a double layer of paperboard forming the lid front panel, 26, and the lock tab, 28a. The lock tab, 28a, engages a lock shelf, 28c, to form the locking mechanism, 28. The lock shelf, 28c, is a z-folded section, 46, formed by two folds, 44, at the top of the first panel flap, 42, proximate to the double layered lid, 20. A half-cut, 38, allows the double layer of the lock tab, 28a, to be more easily formed in the first panel, 14, and also provides a sharper edge which in turn forms a more secure locking mechanism, 28.

[0030] Multiple adhesive portions, 40, affix the double layered lock tab, 28, to itself; affix the z-folded section, 46 to itself; and the double layered lid, 20, to itself. In addition, an adhesive portion, 40a, affixes the top of the first panel, 14, to the interior layer of the lid, 20. A half-cut, 38, positions exterior to the adhesive portion, 40a, allows a user to open the package by lifting the lid, 20, and separating the inner paperboard layer of the lid, as the strength of the paperboard is significantly less than the strength of the adhesive portion affixed to the interior lid, 20, and the top of the first panel, 14. Multiple half-cuts of varying depths are also useful herein, as a half-cut need not necessarily go exactly half way through the paperboard. Furthermore, the depth of the half-cut may be coordinated with various properties of the internal layers of the paperboard (orientation of fibers, laminates, tear strength, etc.), so as to provide the desired peak first opening strength.

[0031] In FIG. 6, a top plan view of a preferred blank, 36, suitable for making the reclosable paperboard package herein, with a close-up of a preferred opening tab, 37, is provided. The package, 10, is preferably formed by folding the blank along the plurality of folds, 44, and half-cuts, 38 and 38a, and affixing an adhesive portion (not shown) in a plurality of locations understood by one skilled in the art. The opening tab, 37, is affixed to the inside lid, 20, preferably with an adhesive portion (not shown), and breaks away during the first opening of the package, 10, as do certain portions which are designated by corresponding half-cuts, 38 and 38a. Thus, half-cuts, 38 and 38a, may be used to either provide breakaway seals, or may be used to promote desired folding, such as for lock tab, 28a. The outer edge of the lock tab, 28a, is straight and therefore provides a larger locking surface than, for example, that of FIG. 3.. Accordingly, the audible locking sound may be greater.

[0032]
FIG. 6 also shows a preferred gripping tab, 48, which provides the consumer with something to more easily grip and pull during any time the lid, 20, is to be lifted. Also present in FIG. 6, are corner tabs, 50, which are folded into the lid to provide structural strength to the corner if the lid, 20. The corner tabs, 50, also serve to provide a smooth and comfortable edge for those consumers who prefer to open the package from the corner, rather than the gripping tab, 48. This may be especially important during the first opening of the package, when the first opening strength is greatest.

[0033] Side glue tabs, 52, in FIG. 6 are shortened by a distance, ε, as compared to the depth, β, of the lid, 20. During formation of the container, glue or similar adhesive (not shown) is applied to the side glue tabs, 52, which are then affixed to the side panels, 18. The distance, ε, increases the flexibility of the lid, 20, and also reduces the peak first opening strength. However, if the distance, ε, is too large, then the peak opening strength may be too small, and therefore the container may accidentally open during shipping or transport. Thus, if present, the distance, ε, is typically from about 10% to about 45% of the depth, β, preferably from about 20% to about 35% of the depth, β, and more preferably from about 25% to about 30% of the depth, β.

[0034] As noted above, the paperboard package is formed of a single piece of paperboard, which significantly reduces manufacturing complexity and raw material costs. The paperboard useful herein is typically from about 0.3 mm to about 4 mm, preferably from about 0.5 mm to about 2 mm in thickness, and has a stiffness of from about 5 (mN)*(m) to about 80 (mN)*(m), preferably from about 15 (mN)*(m) to about 60 (mN)*(m), and more preferably from about 20 (mN)*(m) to about 55 (mN)*(m) in the cross-machine direction, and a stiffness in the machine direction of from about 35 (mN)*(m) to about 120 (mN)*(m), preferably from about 50 (mN)*(m) to about 108 (mN)*(m), and more preferably from about 58 (mN)*(m) to about 100 (mN)*(m). It has now been surprisingly found that the stiffness of the paperboard, in combination with the angle, θ, between the front panel and the lid, significantly contributes to the level of the audible locking sound, as well as the user's impression of how secure the lid is locked.

[0035] The paperboard useful herein may contain a single, or multiple layers of paper, laminate, reinforcing materials, moisture barrier materials, etc. Each layer may be independently oriented, random, unoriented, etc. as desired.

[0036] The package, 10, preferably is used to store a granular material, 30, and especially a granular detergent composition, such as that used to wash laundry. Examples of preferred granular detergents useful herein include those described in, U.S. Pat. No. 5,496,487 to Capeci, et al., issued on Mar. 5, 1996; U.S. Pat. No. 4,963,226 to Chamberlain, issued on Oct. 16, 1990; and U.S. Pat. No. 4,129,511 to Ogoshi, et al., issued on Dec. 12, 1978. In addition, the package, 10, can be used to store any other products where it is desired to provide a freshness seal and/or prevent exposure of the product to the air or moisture, or where repeated opening and closing is desired. While the present invention is described herein with reference to the exemplary six-sided package of FIG. 1, it is contemplated that the present invention can be adapted for use with other package configurations and shapes. For example, the present invention can be used with packages having one or more curved or curvilinear panels and the like. Further, the present invention can be used with top fill and side fill cartons. While the package, 10, is illustrated in FIG. 1 with the lid, 20, disposed at the top of the carton, it is contemplated that the lid, 20, can be placed at other locations, and other lid configurations can be accommodated.

[0037] Sound Pressure Level

[0038] Sound Pressure Level (SPL) is a single measurement of sound pressure in decibels relative to the threshold of hearing which is defined herein as 2×10−5 Newtons per Meter2 or 20 microPascals. When SPL measurements are made, some adjustment for the ear's response to low frequency is usually included. This is done by using filters that follow the Fletcher-Munson curves—the A curve follows F&M at low levels and the B curve follows intermediate levels. The C curve is nearly flat.

[0039] The Fletcher-Munson curves turn down because the loudness curve indicates sensitivity. When a low level and low frequency noise occurs, it is difficult to hear, and thus is not weighted as much as a mid-frequency noise at the same level. SPL is usually measured with special meters that have the weighting curves built in. The A curve is used for soft measurements and the C curve is used for loud sounds. However, for comparative measurements like transmission loss, the “flat” curve is used. The SPL measurement thus has the units of dBSPL.

[0040] The audible locking sound, as defined herein, is measured in a quiet room (background noise level 64-65 dBSPL by a model OS-556 Testo Term sound meter, set to a flat curve. The package to be measured is placed 1 cm from the microphone with the lid opened. The lid is then closed by hand at a normal closing speed, and then the sound pressure level measured and recorded. This is repeated three times, and an average sound pressure level is calculated.

[0041] The audible locking sound useful herein has a sound pressure level of at least about 78 dBSPL, preferably from about 80 dBSPL to about 100 dBSPL, and more preferably from about 81 dBSPL to about 88 dBSPL. Typical paperboard cartons lacking the locking mechanism described herein and/or formed of paperboard not having the stiffness described above typically have a sound pressure level of from about 66 dBSPL to 76 dBSPL.

EXAMPLE 1

[0042] A reclosable paperboard package is formed according to FIG. 3, and has an audible locking sound resembling a “double-click”, and a sound pressure level of 81.7. When in the closed position after the peak first opening, the lid and the first panel are separated by a distance of 4.5 mm. The paperboard has a stiffness of in the machine direction of from 94-102 (mN)*(m) and a stiffness in the cross-machine direction of from 34-37 (mN)*(m), and is about 0.7 mm thick. This package has a peak first opening strength of about 40 N. The paperboard is a sandwich board with a 40 μm polyethylene lamination layer.

EXAMPLE 2

[0043] A reclosable paperboard package is formed according to FIG. 1, except that only two locking mechanisms are present. The package has an audible locking sound resembling a “double-click”, and a sound pressure level of 82.3. When in the closed position after the peak first opening, the lid and the first panel are separated by a distance of at 1.4 mm. The paperboard has a stiffness in the machine direction of from 95-98 (mN)*(m) and a stiffness in the cross-machine direction of from 36-37 (mN)*(m). The paperboard is about 0.7 mm thick. This package has a peak first opening strength of about 40 N. The paperboard is a sandwich board with a 40 μm polyethylene lamination layer.

EXAMPLE 3

[0044] A recloseable paperboard package is formed according to FIG. 6, except that only two locking mechanisms are present. The package has an audible locking sound resembling a “double-click”, and a sound pressure level of 82. When in the closed position after the peak first opening, the lid and the first panel are separated by a distance of at 1.4 mm. The paperboard has a stiffness in the machine direction of from 95-98 (mN)*(m) and a stiffness in the cross-machine direction of from 36-37 (mN)*(m). The paperboard is about 0.7 mm thick, and distance, ε, =27% of the depth, β. This package has a peak first opening strength of about 22 N, due to the distance, ε, and the gripping tab. The paperboard is a sandwich board with a 40 μm polyethylene lamination layer.

[0045] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Paperboard carton having an audible locking sound

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