Adhesive closure strip, bag and method

A closure element incorporated into a flexible bag to reclose a bag opening includes a resilient structure which carries an adhesive strip. The closure element is secured to one wall of the bag and the resilient strip seals the one wall to the respective other wall of the bag when the walls are pressed together and the resilient structure is compressed. The resilient structure is held compressed by the adhesive strip. In one embodiment, the resilient structure includes a base portion and a wing portion which deflects to allow the adhesive strip to make contact with the other wall. In another embodiment, the base portion deflects to flatten against the wing portion, the wing portion secured to the bag wall. The base portion and the wing portion can be provided with engageable elements which snap together or interlock to provide a closing feel to the closure strip as the adhesive strip seals the bag opening.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to recloseable openings, such as for flexible bags. Particularly, the present invention relates to a closure strip using a resealable adhesive portion which at least partly defines a recloseable opening, the closure strip attached to a wall of a flexible bag.

BACKGROUND OF THE INVENTION

Closure strips for recloseable bags are generally known. One type of closure strip includes interlocking profile strips which typically include interlocking tongue and groove elements to seal a bag opening, such as described in U.S. Pat. Nos. 4,756,629, 5,806,984 or 4,909,017.

Another type of closure strip uses a resealable adhesive strip. The resealable adhesive strip uses a removable pressure sensitive adhesive to close a bag opening. A removable pressure sensitive adhesive is one which can be peeled off, together with the backing to which it is applied, from a substrate surface without damage to either the adhesive or the substrate. U.S. Pat. Nos. 5,035,518; 4,645,711; 4,599,265; 4,629,663; 3,608,707; 3,922,464; 4,902,142; and 4,709,399, describe pressure sensitive adhesives and/or packaging using pressure sensitive adhesives.

One drawback to interlocking profile strips is that the strips are relatively thick compared to the thickness of the web material which comprises the front and back wall of the associated bag. This relatively increased thickness is required in order to form the interlocking tongue and groove of the interlocking profile strips. The increased thickness of the profile strip requires higher sealing temperature, pressure and dwell time in the formation of the bag. These additional considerations adversely affect the speed and throughput of the bag forming machines.

Resealable adhesive strips suffer the drawback that the strips lack a positive closing which gives the user indication or feedback of a complete closure of the resealable bag.

The present inventor has recognized that it would be advantageous to provide a recloseable strip for a bag that has a low profile thickness and which also provides a positive closure indication to the user.

SUMMARY OF THE INVENTION

The present invention provides a recloseable closure strip for an opening, such as for a flexible bag. The closure strip includes an adhesive region and at least one flexible member which deflects during engagement of the adhesive region to an adhesive receiving region of the bag during re-sealing. The deflection of the flexible member provides a positive closing indication or feedback to the user during re-sealing.

The flexible member can be part of a resilient structure which carries the adhesive region such that by engaging the closure strip to reclose the bag, the resilient structure is compressed or squeezed from a relaxed or uncompressed condition to a flattened condition, giving the user a positive feel or indication of the re-sealing of the bag opening. The resilient structure can be significantly thinner in profile than the prior known interlocking profile strips due to the fact that it is functioning only as an indication of sufficient re-sealing pressure and does not perform a sealing function.

The bag can include a companion strip to the closure strip, the companion strip providing an adhesive receiving area or land for the adhesive region of the closure strip. The companion strip can be plain or can have a coacting adhesive applied thereto. The adhesive region of the closure strip and the land of the companion strip can include, rather than tacky adhesives, cold sealable, pressure sensitive cohesives which are adherent to each other and are not tacky and adherent to other surfaces.

The closure strip of the invention can include interlocking elements which interlock when the resilient structure is compressed to its flattened condition simultaneously with the adhesive strip contacting the land, to give the user a positive indication of the re-sealing of the bag opening. The resilient structure can include a base portion and a wing portion, one of which is connected to a first wall of the bag, the wing portion extending obliquely from the base portion, and the base portion carrying the adhesive strip. The interlocking elements can be applied one on the base portion and one on the wing portion to interlock when the base portion and the wing portion are flattened together.

The interlocking portions function differently than that of conventional closures since they do not lock the closure, but instead only give the closure the same feel or indication of re-sealing as do interlocking closures, but which utilizes an adhesive as the re-sealing means with the adhesive acting independently of the interlocking action of the interlocking portions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a bag 15 having a front wall 16 a and a back wall 16 b . The bag is formed by folding a sheet of web material and forming a longitudinal seam 25 on the back wall 16 b . The bag is sealed between the front wall 16 a and the back wall 16 b at a top seam 40 and at a bottom seam 42 . A line of perforations 43 can be provided along the top seam 40 for initially opening the bag. Alternatively, the top seal 40 can be a non-resealable adhesive or a heat seal as is known, which can be pulled open to initially open the bag. A closure element 20 is applied transversely to the longitudinal direction or formation axis A of the bag 15 . The formation axis A is that axis, along which bags are formed connected end-to-end and thereafter separated to form individual bags. The bags and closure elements can be assembled in an apparatus as described in U.S. Pat. Nos. 4,909,017; 3,608,707; 4,617,683; or 6,003,582, all herein incorporated by reference.

FIG. 1A illustrates a bag 115 , which is formed along an alternate formation axis A . Bags in this embodiment are connected side-by-side along the formation axis A before being separated into individual bags. In this bag 115 , the closure element 20 is arranged longitudinally, parallel to the formation axis A .

FIG. 1B illustrates a bag 215 which is formed along the formation axis A as in FIG. 1 . In this bag 215 however, the closure element 20 is arranged longitudinally, parallel to the formation axis A.

FIG. 2 illustrates a closure element 20 secured to the front wall 16 a of the bag 15 , 115 , by a known method, such as by a heat seal 23 . Alternately, the closure element could be secured to the back wall 16 b of the bag.

In this embodiment, the closure element 20 is shaped as a trough 22 with wing portions 22 a , 22 b which diverge from a base portion 22 c . A resealable adhesive layer or strip 24 is arranged along the trough 22 on the base portion 22 c . The adhesive layer can be a removable pressure sensitive adhesive such as described in U.S. Pat. Nos. 5,035,518; 4,645,711; 4,599,265; 4,629,663; 3,608,707; 3,922,464; 4,902,142; and 4,709,399, all herein incorporated by reference. Between the back wall 16 b and the adhesive strip 24 , a bag opening 17 is defined.

FIG. 2A illustrates in perspective the closure strip 20 isolated from the remaining bag components. The strip 20 includes a trough-like structure formed by the wing portions 22 a , 22 b and the base portion 22 c . The adhesive portions 24 is applied onto the base portion 22 c along the length of the element 20 .

FIG. 2B illustrates that the closure element 20 can be wound in a spool 50 . The closure element material can thereafter be dispensed, cut and applied to individual bags in an apparatus, such as described in U.S. Pat. Nos. 4,617,683 or 6,003,582, for applying profile strip fasteners.

As illustrated in FIG. 3 , the back wall 16 b and the front wall 16 a are compressed together by a user's fingers to close the bag opening 17 . This action compresses or flattens the trough 22 , by resiliently flattening the wing portions 22 a , 22 b until the adhesive layer 24 is contacted against the front wall 16 a . The adhesive layer 24 has a sufficiently strong adherence to the back wall 16 b to retain the wing portions 22 a , 22 b in their flattened states.

Unlike prior known adhesive tapes used to create recloseable bags, the present configuration allows the user the ability to feel the closure strip flex and seal to determine whether the seal is positively closed. The wing portions 22 a , 22 b create a spring effect. This feature allows the user to recognize the indication that a positive closure has been achieved since the overall thickness of the closure element 20 is substantially decreased when compressed and retained into the closed condition. Additionally, a failure of the adhesive layer 24 to adequately seal is indicated if the adherence is insufficient to retain the resilient wing portions 22 a , 22 b in their flattened state, i.e., the closure element 20 will spring to its uncompressed, thicker, profile.

An additional advantage of the embodiment of FIGS. 2 and 3 is that when the closure element 20 is compressed flat it is substantially only a single thickness closure which can approach the same thickness as the bag wall material as shown in FIG. 3 .

As illustrated in FIG. 4 , a second strip or a companion strip 29 can be arranged on the back wall 16 b opposite the closure element. The second strip 29 can carry an adhesive layer 30 facing the closure element.

FIG. 4 also illustrates a modified closure element 20 which includes wing adhesive portions 24 a , 24 b applied onto the wing portions 22 a , 22 b respectively. When the back wall 16 b is compressed toward the front wall 16 a , the second strip 29 flattens the wing portions 22 a , 22 b against the back wall 16 b . The adhesive regions 24 , 24 a , 24 b compress against the adhesive region 30 to close the opening 17 defined between the modified closure element 20 and the second strip 29 .

The adhesive strips 24 , 24 a , 24 b and 30 can be formed from coadhesives, as known in the art, that will only adhere to like coadhesives, thereby resisting potential contamination from particles of the contained product within the bag, or external particles. A cold sealable, pressure-sensitive cohesive, such as described in U.S. Pat. No. 4,898,787, can be applied to the closure strip and the companion strip. This cohesive has low surface tack and is cohesive only when placed under pressure in contact with other cold sealable cohesive coated surfaces. Thus, the closure strip and the companion strip would not be tacky and adherent to non-coated surfaces such as the product held in the bag, or debris.

An additional advantage of the configurations described in FIG. 4 is that when the bag walls 16 a , 16 b are initially compressed together to seal the opening 17 , the adhesive regions 24 a , 24 b first seal against the front wall 16 a or the additional strip 29 (with or without adhesive layer 30 ) forming a prone trapezoidal profile channel before the closure 20 is completely flattened. This trapezoidal channel will progress along the length of the closure 20 as the closure is progressively sealed by the user's fingers sliding along the length of the closure element through the bag walls. As the user's fingers reach the end of the closure element, air trapped within the trapezoidal space is expelled (with a snap sound) which gives the user an additional feedback or indication that the bag has been sealed with sufficient pressure.

FIG. 5 illustrates an alternate closure element 220 having wing portions 222 a , 222 b that are arranged angled toward each other inwardly, having a decreasing clearance between wing portions taken forwardly of the base portion 222 c . During closing, the wing portions are resiliently compressed until the adhesive region 224 engages the front wall 16 a , or alternately, engages a companion strip 29 such as illustrated in FIG. 4 . The wing portions 222 a , 222 b are folded against the base 222 c and have a length such as to not interfere with the adhesive portion 224 .

FIG. 6 illustrates a further alternate embodiment closure element 300 connected to the front wall 16 a , and a second strip 304 connected to the back wall 16 b . The closure element 300 and the second strip 304 are substantially in alignment. The elements 300 , 304 are connected by heat sealing, or other known method, to the bag walls 16 a , 16 b , respectively. The closure element 300 includes at least one base portion 306 carrying an adhesive region 324 which faces the second strip 304 . The base portion 306 is connected to a wing portion 330 . The wing portion 330 is heat sealed or otherwise secured to the front wall 16 a.

The base portion 306 and the wing portion 330 have formations which lock together when the base portion is flattened by pressing force from the strip 304 . Particularly, the base portion 306 has a hook portion 336 which engages an angled edge or face 338 of the wing portion 330 . The locking engagement provides a sensory field to the user that the closure element 300 is being sufficiently sealed to the strip 304 .

Although a second strip 304 is illustrated, in some applications, the second strip can be eliminated and the adhesive strip 324 sealed directly to the bag back wall 16 b . Alternately, a second strip of adhesive can be applied to the second strip or to the back wall to engage the adhesive strip 324 such as the arrangement illustrated in FIG. 4 .

FIG. 7 illustrates the closure element of FIG. 6 in a closed condition. The base portion 306 is pressed flat to the wing portion 330 , and the hook portion 336 has engaged the edge 338 of the wing portion 330 in a snap-fitting fashion to give the user a positive indication of the complete closure of the bag opening.

FIG. 8 illustrates another embodiment closure element 400 which includes a base portion 406 resiliently attached to a wing portion 430 . The base portion 406 carries an adhesive strip 424 facing the back wall 16 b of the bag. When the bag is closed, the back wall 16 b engages the adhesive strip 424 to seal the bag opening. A second strip can be applied to the bag opposite to the closure element 400 , such as shown as 304 in FIGS. 6 and 7 . Also, a second strip of adhesive can be applied to the second strip or to the back wall to engage the adhesive strip 424 such as illustrated in FIG. 4 .

The base portion 406 includes a tongue portion 440 which is aligned to register with a groove 442 formed in the wing portion 430 . The tongue portion is sufficiently sized to provide a resilient fit or squeeze fit within the groove so that a user is provided with a positive feel of resealing the bag. The pressure required to seat the tongue portion 440 within the groove is sufficient to ensure that the adhesive has been sufficiently pressed to the back wall 16 b (or to the second strip on the back wall as applicable).

An additional advantage of the closure element embodiments of FIGS. 2 through 5 is that the wing portions are such as to tend to shelter the adhesive strip from contamination, particularly from products being removed from the bag, past the closure strip. The products tend to be directed or deflected away from the adhesive portion by the presence of the extending wing portions.

Although in the above embodiments the closure strip is described as being attached to the front wall of the bag, the closure strip could be attached to the back wall of the bag and any companion strip attached to the front wall of the bag without departing from the scope of the invention.

Many of the various embodiments of the invention could be interchanged, such as the companion strip of FIG. 4 and FIG. 6 and the cohesive properties of the closure of FIG. 4 could be utilized by any of the embodiments, given an application of cohesive material on the strip and on the coacting companion strip or bag wall. The bags of FIGS. 1 , 1 A or 1 B could be formed with the closure strips at an orientation other than those illustrated such as rotated 90 , to name just a few examples.