Resealable and Reclosable Packaging Having Reduced-Curl, Pressure-Sensitive Seal Tape

Abstract

A flexible package formed from a film of polymer packaging material having a first and second panels sealed at a top portion and a bottom portion, an elongate slit in the first panel, and an elongate strip of pressure-sensitive-adhesion, re-closing tape (“PSA tape strip”) applied to the surface of said first panel over the slit. The PSA tape strip has an adhesive edge portion abridging and releasably sealing the slit and a non-adhesive edge portion arranged on one side of said slit and lying against the first panel. The PSA tape strip is adapted so that the slit can be unsealed by gripping the non-adhesive edge portion and pulling the PSA tape strip away from the first panel until the adhesive edge portion no longer abridges the slit. The PSA tape strip comprises a base material of polymer film that is compatibly recyclable with said packaging material The PSA tape strip also resists curling when it is strained by pulling it away from said first panel to unseal the slit. Preferably, the PSA tape has secant modulus ratio (machine direction to cross direction) greater than 90%.

Claims

1. A flexible package formed from a film of polymer packaging material, comprising: a. a first and second panels sealed at a top portion and a bottom portion; b. an elongate slit in said first panel; and, c. an elongate strip of pressure-sensitive-adhesion, re-closing tape (“PSA tape strip”) applied to the surface of said first panel over said slit, said PSA tape strip having an adhesive edge portion abridging and releasably sealing said slit and a non-adhesive edge portion arranged on one side of said slit and lying against said first panel, said PSA tape strip adapted so that said slit can be unsealed by gripping said non-adhesive edge portion and pulling said PSA tape strip away from said first panel until the adhesive edge portion no longer abridges said slit, wherein said PSA tape strip comprises a base material of polymer film that is compatibly recyclable with said packaging material; and, wherein said PSA tape strip resists curling when it is strained by pulling it away from said first panel to unseal said slit.

2. The package recited in claim 1, wherein said PSA tape strip comprises a base material of polymer film, a pressure-sensitive adhesive applied to a first side of said base material, and a non-adhesive grip strip of polymer film applied to said adhesive along one edge of said first side of said base material to form said non-adhesive edge portion, and the remainder of said first side forming said adhesive edge portion, wherein said grip strip is compatibly recyclable with said packaging material.

3. The package recited in claim 1, wherein said PSA tape strip comprises a base material of polymer film, a pressure-sensitive adhesive applied to a first side of said base along one edge in a pattern less than the width of said tape strip to form said adhesive edge portion, and the remainder of said first side having no adhesive applied thereto and forming said non-adhesive edge portion.

4. The package recited in claim 1, wherein said PSA tape strip has a percentage curl less than about 5%.

5. The package recited in claim 1, wherein said base material comprises machine-direction-oriented polyethylene film produced from a blown film process having a multilayer film structure of at least 3 but less than 8 layers.

6. The package recited in claim 5, wherein said base material has a stretch ratio of 1:3 but no greater than 1:10.

7. The package recited in claim 5, wherein said base material contains 25 to 65 percent by weight of HDPE, combined with a blend of metallocene LLDPEs and higher alpha olefin LLDPE utilizing butene, hexene, or octane, said blend comprising 10 to 90 percent by weight of metallocene LLDPE.

8. The package recited in claim 5, wherein said base material has a thickness of at least 1.6 mils but less than 2.5 mils.

9. The package recited in claim 5, wherein said base material has a haze value less than 10%.

10. The package recited in claim 5, wherein at least one side of said base has been corona treated to a surface tension of at least 36 dynes/cm but less than 46 dynes/cm.

11. The package recited in claim 5, wherein said base has a secant modulus between 130,000 to 250,000 p.s.i. in the machine direction and 100,000 to 225,000 p.s.i. in the cross direction, and a secant modulus ratio (machine direction to cross direction) greater than 90%.

12. A resealable, pressure-sensitive-adhesion tape (“PSA tape”) for use in combination with a flexible package formed from a film of polymer packaging material, said PSA tape comprising: a. a base material of polyethylene film that is compatibly recyclable with said packaging material; and, b. a pressure sensitive adhesive applied to one side of said base material along one at least a lengthwise-extending edge to form an adhesive edge portion and a non-adhesive edge portion; wherein said PSA tape strip comprises a base material of polymer film that is compatibly recyclable with said packaging material; and, wherein said PSA tape resists curling when it removed from a surface to which it has been adhered by pulling on said non-adhesive edge portion.

13. The PSA tape recited in claim 12, including pressure-sensitive adhesive applied to the entirety of one side of said base material, and a grip strip of polymer film applied to said pressure-sensitive adhesive along one edge of said first side of said base material to form said non-adhesive edge portion, and the remainder of said first side forming said adhesive edge portion, wherein said grip strip and said pressure-sensitive adhesive are compatibly recyclable with said packaging material.

14. The PSA tape recited in claim 12, wherein said PSA tape strip has a percentage curl less than about 5%.

15. The PSA tape recited in claim 12 having secant modulus ratio (machine direction to cross direction) greater than 90%.

16. The PSA tape recited in claim 14, wherein said base material: a. comprises a machine-direction-oriented polyethylene film produced from a blown film process having a multilayer film structure of at least 3 but less than 8 layers; b. has a stretch ratio of 1:3 but no greater than 1:10; c. contains 25 to 65 percent by weight of HDPE, combined with a blend of metallocene LLDPEs and higher alpha olefin LLDPE utilizing butene, hexene, or octane, said blend comprising 10 to 90 percent by weight of metallocene LLDPE; d. has a film thickness of 1.6 mils to 2.5 mils; e. has a haze value less than 10%; f. has been corona treated on at least one side to a surface tension of at least 36 dynes/cm but less than 46 dynes/cm; and, g. has a secant modulus between 130,000 to 250,000 p.s.i. in the machine direction and 100,000 to 225,000 p.s.i. in the cross direction.

17. The PSA tape recited in claim 13, wherein said adhesive coating has a thickness from 0.6 to 1.1 mils.

18. The PSA tape recited in claim 17, wherein said pressure-sensitive adhesive is selected from the group consisting of: solvent based acrylic or rubber based, aqueous based, formulated styrenic isoprene or formulated styrenic butadiene block copolymer hot melt adhesive or Ultra Violet Light (UV C) hot melt acrylics.

19. The PSA tape recited in claim 13, wherein said grip strip comprises either polyethylene or polypropylene film.

20. The PSA tape recited in claim 12, wherein the width of said non-adhesive edge portion is at least ½ in.

21. The PSA tape recited in claim 12, wherein said tape is formed as a continuous roll or a series of segmented labels.

22. The PSA tape recited in claim 12, including pressure-sensitive adhesive applied to the entirety of one side of said base material, and a water based or UV cure deadeners used in the label industry applied to said pressure-sensitive adhesive along one edge of said first side of said base material to form said non-adhesive edge portion, and the remainder of said first side forming said adhesive edge portion.

23. The PSA tape recited in claim 14, wherein said base material comprises a multilayer bi-axially-oriented, polyethylene-based film having: a. a core layer formed of a core resin composition comprising a blend of 50 to 90% by weight of a first metallocene linear low density polyethylene (mLLDPE) resin having a melt index from about 0.8 dg/s to about 2 dg/s, about 5-25% by weight of a second mLLDPE resin having melt index from about 0.1 dg/s to about 0.8 dg/s, and about 5-25% by weight of a third mLLDPE resin having a melt index from about 2 dg/s to about 10 dg/s; and b. a skin layer having a skin resin composition comprising one or more polyolefin plastomers, wherein said skin layer has a thickness of approximately 3% to 20% as compared to a total thickness of the extruded, oriented, multilayer, film structure.

24. The PSA tape recited in 23, wherein said film: a. has a film thickness of at least 1.6 mils but less than 2.5 mils; b. has a haze value less than 10%; c. has at least one side corona treated to a surface tension of at least 36 dynes/cm but less than 46 dynes/cm.

25. The PSA tape recited in claim 24, wherein said pressure-sensitive adhesive: a. has a thickness of 0.6 to 1.1 mils; and, b. is selected from the group consisting essentially of: solvent based acrylic or rubber based, aqueous based, formulated styrenic isoprene or formulated styrenic butadiene block copolymer hot melt adhesive or Ultra Violet Light (UV C) hot melt acrylics.

26. A resealable, pressure-sensitive-adhesion tape (“PSA tape”) for use in combination with a flexible package formed from a film of polymer packaging material, said PSA tape comprising: a. a base material of polyethylene film comprising a machine-direction-oriented polyethylene film produced having a multilayer film structure of at least 3 but less than 8 layers; b. a pressure sensitive adhesive applied to a first side of said base material, said pressure sensitive adhesive selected from the group consisting essentially of: solvent based acrylic or rubber based, aqueous based, formulated styrenic isoprene or formulated styrenic butadiene block copolymer hot melt adhesive or Ultra Violet Light (UV C) hot melt acrylics; c. a non-adhesive grip strip of polymer film applied to said adhesive along one edge of said first side of said base material to form a non-adhesive edge portion, and the remainder of said first side forming an adhesive edge portion, wherein said grip strip comprises either polyethylene or polypropylene film; wherein said PSA tape has secant modulus ratio (machine direction to cross direction) greater than 90%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a flexible package in accordance with a preferred embodiment of the invention;

[0030] FIG. 2 is an enlarged section of the package shown in FIG. 1, which illustrates opening the package by pealing back an elongate stripe of pressure-sensitive-adhesion tape in accordance with an embodiment of the invention;

[0031] FIG. 3 is a top plan view (not to scale) of a section of schematic illustration of a pressure-sensitive-adhesion tape in accordance with an embodiment of the invention;

[0032] FIG. 4 is a cross-sectional view (not to scale) of a pressure-sensitive-adhesion tape in accordance with an embodiment of the invention;

[0033] FIG. 5 is a fragmented perspective view of a pressure-sensitive-adhesion tape applied to a film of packaging material during in accordance with an embodiment of the invention;

[0034] FIG. 6 is a schematic illustration of a pressure-sensitive-adhesion tape in accordance with an embodiment of the invention illustrating the width of the seal zone and anchor zone;

[0035] FIGS. 7 and 8 are perspective views of a flexible package in accordance with an embodiment of the invention in the closed and open configuration, respectively;

[0036] FIGS. 9 and 10 are perspective views of a flexible package in accordance with an embodiment of the invention in the re-closed configuration; and,

[0037] FIG. 11 is a schematic illustration of a method of producing a flexible package in accordance with a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] For the purpose of illustrating the invention, several embodiments of the invention are shown in the accompanying drawings. However, it should be understood by those of ordinary skill in the art that the invention is not limited to the precise arrangements and instrumentalities shown therein and described below. Throughout the specification, like reference numerals are used to designate like elements.

[0039] Throughout the drawings, the various embodiments are illustrated using transparent materials so that the package contents can be seen. However, it should be appreciated by those of ordinary skill in the art that the embodiments may be made from opaque or printed material without departing from the intended scope of the invention.

[0040] Throughout the specification, as used in connection with various elements and portions of elements, the following definitions apply.

[0041] The terms “Polyethylene” or “ethylene-based polymer” shall mean polymers comprising greater than 50% by weight of units which have been derived from ethylene monomer as described in U.S. Pat. No. 11,214,047. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m-LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE). These polyethylene materials are generally known in the art; however the following descriptions may be helpful in understanding the differences between some of these different polyethylene resins.

[0042] The term “LLDPE”, includes both resin made using the traditional Ziegler-Natta catalyst systems as well as single-site catalysts, including, but not limited to, bis-metallocene catalysts (sometimes referred to as “m-LLDPE”) and constrained geometry catalysts, and includes linear, substantially linear or heterogeneous polyethylene copolymers or homopolymers. LLDPEs contain less long chain branching than LDPEs and includes the substantially linear ethylene polymers, which are further defined in U.S. Pat. Nos. 5,272,236, 5,278,272, 5,582,923 and 5,733,155; the homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and/or blends thereof (such as those disclosed in U.S. Pat. Nos. 3,914,342 and 5,854,045). The LLDPEs can be made via gas-phase, solution-phase or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art, with gas and slurry phase reactors being most preferred. Similarly the Ziegler-Natta catalyst used in higher alpha olefin LLDPE are commonly based on butene, hexene, or octene copolymerized in the presence of ethylene.

[0043] The term “HDPE” refers to polyethylenes having densities greater than about 0.935 g/cm.sup.3, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometry catalysts.

[0044] The term “curl” means the tendency of a web (or multi-layer web) of material to deviate from a generally flat or planar orientation when there are no external forces on the web. “Curl percentage” or “curl %” shall mean the percentage change in width of a 1 in. wide by 6 in. long test sample using the testing procedure described below in ASTM Method for peel adhesion. The degree of curl is determined by measuring the change of width of the 1 inch wide tape at 2.5 in. down the 6 in. test strip that was applied to the test panel.

[0045] A package in accordance with an embodiment of the invention is shown in FIG. 1 and is designated generally by reference numeral 10. The package 10 has a conventional construction and was formed on an FFS machine by folding flexible packaging film 8 into a tube with lateral edges of the film being heat welded along a longitudinal seam 14 at the rear of the package as shown, for example, in FIG. 1. Heat seal welds 15 at the top and bottom of the package complete its construction.

[0046] The package 10 has a front panel 11 that was formed with a lateral (widthwise-extending) slit 13 that functions as the resealable opening for the package 10. The slit 13 is covered by a strip of resealable PSA seal tape 12. In this embodiment, the slit 13 extends the entire width of the package while the seal tape spans the entire width of the package and wraps around the sides edges of the package and adheres to the rear panel. In other preferred embodiments the opening may have a different configuration, such as an elongated hole, so long as its dimensions are proportioned so that PSA seal tape adheres to a sufficient amount of surrounding package material to create the sealing force for the package's intended application. In further preferred embodiments, the PSA tape 12 need not wrap around the sides or even extend along the entire width of the package so long as the tape is proportioned to cover the entire slit 13.

[0047] The construction of the PSA seal tape 12 comprises a base material 23, a pressure sensitive adhesive 25, and a grip strip 27, and is schematically illustrated in FIGS. 3-4, which are not to scale. In one preferred embodiment, the adhesive 25 is applied to the entire surface of one side of the base material 23. The grip strip 27 is adhered to the base material 23 by the pressure-sensitive adhesive 25. When used in common consumer food packaging, the PSA seal tape may be about 1 to 1.25 in. wide, and the grip strip 27 is about 0.3 to 0.5 the width of the tape base. In other applications, the width of the PSA seal tape 12 may vary in proportion to the size of the package and the force needed to seal the opening. In preferred embodiments of all sizes, the grip strip extends along the entire length of the PSA seal tape. The slit of the package is unsealed and opened by peeling the PSA seal tape off the package by pulling the grip strip 27 as shown in FIG. 2.

[0048] The tape base 23 and grip strip 27 are made from a flexible, polymer material that is compatibly-recyclable with polyethylene packaging, including HDPE, and has good resistance to curling under strain. In preferred embodiments, the tape base material has a thickness range between 1.5 and 3 mils, preferably 1.6 to 2.0 mils. In preferred embodiments, the grip strip has a thickness range between 0.5 and 2.0 mils, more preferably 0.9 to 1.4. The pressure-sensitive adhesive is applied in a thickness of range between and 0.6 and 1.0 mils. To insure good recycle compatibility, in a preferred embodiment, the overall adhesive content from the PSA tape is less than about 5% of the total weight of the package to which the PSA tape is adhered.

[0049] Materials suitable for use in the PSA tapes of the invention are machine-direction-oriented polyethylene film produced from a blown film process. The orientation ratio is between 1:4 and 1:10, meaning that the length of the film has been increased by between a factor of 4 and 10. The resins may be blends of metallocene LLDPEs, higher alphaolefin LLDPEs, and HDPEs. The materials should have good thermal stability with minimal film shrinkage at 120° C., and surface energy of about 38-44 dynes. The secant modulus is preferably approximately 3× higher than traditional PE films used at similar gauges. The tape materials should preferably have the additional properties recited in Table 1:

TABLE-US-00001 TABLE 1 Preferred Value ASTM Attribute Range Units Test Method Gauge 2.0 +/− 20%  mil Yield@ 1 mil 29,195 +/− 20%    in.sup.2/lb Haze   5-15% % D-1003 Gloss 45° 65 +/− 20% % D2457 Tensile Strength MD 27,400 psi D-882 TD 4,900 +/− 20%   .sup.  Elongation MD 50 % D-882 TD 25 +/− 20%  .sup.   Secant Modulus in the 130,000-250,000 psi D-882 machine direction Secant Modulus in the 100,000-225,000 Psi D-882 transverse direction Tear Propagation 125 g D-1922 300 +/− 20%  Dart Impact 40 +/− 20% g D-1709 - Method B O2 TR 65.00 +/− 20%   cc/100 in.sup.2/24 hr D-3985 (0% RH, 23° C.) MVTR 0.17 +/− 20%.sup.  g/100 in.sup.2/24 hr F-1249 (90% RH, 100° F.)

[0050] In one exemplary preferred embodiment, the tape base was formed from 2.0 mil GAP-2501 machine-direction-oriented polyethylene film (formerly GAP-1501) and the grip strip was formed from GAP 1001, both of which are manufactured by Charter Next Generation, Inc., Milton, Wis.

Example 1

[0051] An acrylic emulsion pressure-sensitive adhesive formulated with a low level of Dow Chemical CR 9-101, an isocyanate coreactant (formulated at a level less than 1% CR 9-101 per solid part of acrylic emulsion), was applied directly to a 2 mil film of machine-direction-oriented polyethylene sold by Chart Next Generation, Inc., Milton, Wis., under catalog GAP-1001 (“Film A”), and for comparison, to a 2 mil film of GAP-2501 formerly sold under the name GAP-1501 (“Film B”). The isocyanate was used to improve the anchorage of the adhesive to the corona treated polyethylene films. Both films were also corona treated to raise the surface energy to greater than 40 dynes/cm to help increase anchorage of the adhesive to the film. The adhesive was dried in a coating process. To achieve a residual retained moisture less than 0.5% in the adhesive film using, oven conditions in a ramped profile from 150-220° F. in a multi-zoned forced air drying process were used. The films were then wound into a master roll of self-wound adhesive tape. The thickness of the adhesive coat on both films was 0.9 mils (24 g/m.sup.2). Those skilled in the arts understand that adhesive anchorage of pressure sensitive adhesives can be achieved in numerous way including the addition of external crosslinkers such as isocyanate chemistries, aziridines, carbodiimides, multi-layer coatings in addition to optimal levels of corona treatment. A standard 2 mil polypropylene tape, Amtopp TT-50 (“Film C”), manufactured by Inteplast Group, Livingston, N.J., treated with a similar acrylic emulsion from Dow Chemical sold under the trademarks Robond™ PS-90, Robond™ PS-2000 type, was used as a control. The typical properties of the films are described in Table 1.

TABLE-US-00002 TABLE 2 Reference ASTM Property Film A Film B Tape C Method Gauge 2 mil 2 mil 2 mil Yield at 1 mil (in.sup.2/lb) 29,500 29,125 16,500 Haze % 5 10 2 D-1003 Tensile md/cd (lb/in.sup.2) 23,900/5200   27,400/4900   20,000/38,000 D-882 Elongation md/cd (%)  90/100 50/25 150/55  D-882 Secant Modulus md/cd (lb/in.sup.2) 158,700/207,200 235,500/199,350 D-882 Tear 100/125 125/300 D-1922 MVTR g/100 in.sup.2/24 hr 0.55 0.17 F-1249 (90% RH, 100 F.)

[0052] The two tapes created from Films A and B and Reference Tape C were evaluated for peel adhesion and curl behavior. Specifically, peel was measured by applying 1 in. wide samples of each tape to a Chemsultants™ stainless steel test panel using the procedures outlined in ASTM Method 3330 for peel adhesion. These panels are stainless steel, 50 by 125 mm (2 by 5 in) no less than 1.1 mm (0.043 in.) thick, conform to Type 302 or 304 of Specification ASTM A666, and have a bright annealed finish. The surface roughness height shall be 50±25 nm (2.0±1.0 uin.) arithmetical average deviations from the mean line. A smooth, 4.5 lb. stainless steel roller was used to apply the test tapes to the panel. A one minute dwell time was used prior to measuring the peel force and curl behavior of each sample. The peel force was measured using an SP-2100 Slip Peel Tester from Imass Inc., Accord, Mass. Those skilled in the art of pressure sensitive adhesives will understand that the use of a stainless-steel surface represents a standardized method to measure adhesion and the tapes response to deformation for an applied force. This methodology is the basis to reproducibly mimic the forces that a consumer may apply to a reseal tape feature which may be applied on to a film surface ranging for 32 dynes/cm (Untreated Polyethylene or Polypropylene packaging films) to >40 dynes/cm for a Polyester film, printed or matte coated film, or treated film. The degree of curl was determined by measuring the change of width of the 1 inch wide tape at 2.5 in. down the 6 in. test strip that was applied to the test panel. This way the measurement for film thickness change was determined at the same spot between samples. The reduction in width was recorded for each sample. The results of this evaluation are recorded in table 3. Curl % was recorded as the change of width of the 1 in. test strip divided by the original width multiplied by 100%.

TABLE-US-00003 TABLE 3 Property Tape A Tape B Reference Tape C 180 degree Stainless Steel 335 325 653 Peel Adhesion (grams/in) Curl % 18.8% 0% 0%

[0053] The results in Table 3 show that the preferred inventive Tape B possesses approximately equivalent peel adhesion to Tape A but has much improved curl resistance. While Tape C had the best adhesion and curl resistance, it is not compatibly recyclable with HDPE packaging.

[0054] The typical property values for Film B are listed in Table 4.

TABLE-US-00004 TABLE 4 Typical ASTM Test Attribute Value Units Method Gauge 2.00 mil Yield@ 1 mil 29,195 in.sup.2/lb Haze 10 % D-1003 Gloss 45° 65 % D2457 Tensile MD 27,400 psi D-882 TD 4,900 Elongation MD 50 % D-882 TD 25 Secant MD 235,500 psi D-882 Modulus TD 199,350 Tear MD 125 g D-1922 TD 300 Dart Impact 40 g D-1709 - Method B O2 TR 65.00 cc/100 in.sup.2/24 hr D-3985 (0% RH, 23° C.) MVTR 0.17 g/100 in.sup.2/24 hr F-1249 (90% RH, 100° F.)
One of ordinary skill in the art should appreciate that the intended application of the PSA tape is to a flexible polymer packaging material, not a stainless steel sheet such as described above. However, it should also be appreciated that the inventive PSA tape may be applied to numerous different polymer surfaces with different surface properties, such has polyethylene and polyester. For example, polyethylene may have a typical base surface energy of 30 dyne, which would yield lower adhesion an introduce less strain and ultimately less curl to the tape when you use it, compared to one that is corona treated to 42 dynes, which would introduce a higher grab and then ultimately more strain and then curl when you peel the tape off of a higher energy surface. By comparison, the adhesive has a greater inherent ability to adhere to polyester because of the surface energy and the chemistry of the surface itself (more polar than PE). ASTM Method 3330 for peel adhesion provides one test method for measuring and thus quantifying the low curl percentage of the invention.

Example 2

[0055] An acrylic UV cure, hot melt, pressure sensitive adhesive was applied directly to two machine-direction-oriented polyethylene films at 2 mil thickness sold by Chart Next Generation, Inc., Milton, Wis., under catalog no. GAP-1001 (“Film A”), and catalog no. GAP 2501 formerly known as GAP-1501 (“Film B”). Both films were corona treated to raise the surface energy to greater than 40 dynes/cm to help increase anchorage of the adhesive to the film. The adhesive was cured at 20 mJ/cm.sup.2 UV-C Dosage in a coating process and wound into a master roll of self-wound adhesive tape. The thickness of the adhesive coat on both films was 0.9 mils (24 g/m.sup.2). Each of the roll stocks were then slit into 1.125 in. narrow tapes and had a 0.9 mil grip strip of XCC-18167 (“Film C”), manufactured by Charger Next Generation, Inc., laminated to create a dry edge onto the tape.

[0056] The properties of the untreated PE films are listed below.

TABLE-US-00005 TABLE 5 ASTM Property Film A Film B Film C Method Gauge 2 mil 2 mil 0.9 mil Yield at 1 mil (in.sup.2/lb) 29,500 29,125 16,500 Haze % 5 10 5 D-1003 Tensile md/cd (lb/in.sup.2) 23,900/5,200  27,400/4,900  23,900/5200   D-882 Elongation md/cd (%)  90/100 50/25  90/100 D-882 Secant Modulus md/cd (lb/in.sup.2) 158,700/207,200 235,500/199,350 158,700/207,200 D-882 Ratio Secant Modulus MD/CD % 76.6 118 76.6 Tear 100/125 125/300 100/125 D-1922 MVTR g/100 in.sup.2/24 hr 0.55 0.17 0.55 F-1249 (90% RH, 100 F.)

[0057] The two tapes created from the films, were evaluated for reseal performance in a resealable package application. Tapes 1 and 2 comprise the combination of Films A+C and Films B+C, respectively. Specifically, a 5 in. by 8 in. package of the configuration shown in FIGS. 1 and 2 was formed using a three-layer packaging film schematically illustrated below:

TABLE-US-00006 exterior side of bag Film 1 - 0.9 mil GAP-1001 PE Print Web (clear) PE film from CNG Films Film 2 - 2.0 mil GA-NDPS-P2 (white) PE film from CNG films Film 3 - 2.25 mil GA-RX100LBV Sealant (clear) EVA/PA sealant film from CNG films interior (contents) side of bag

[0058] The inward facing side of Film 1 was corona treated to greater than 40 dynes/cm for print receptivity. The outside layer of Film 1 was not corona treated and was at 32 dynes/cm surface tension for this specific testing.

[0059] The peel and reseal test protocol involves opening and then resealing Tape 1 and Tape 2 over the package slit. When the seal tape is initially applied to the package, the entire width of the adhesive portion of the tape, i.e., excluding the grip strip, is adhered to the package and straddles the slit as best seen in FIGS. 1 and 6. The width of the tape on the top side of the slit that re-adheres to the package is illustrated in FIG. 6, identified by reference letters “WRZ”, and is hereinafter referred to as the seal zone width. The width of the tape on the bottom side of the slit that stays adhered (anchored) to the package is identified by reference letters “WAZ” and is referred to as the anchor zone width. Both tapes had a 6 mm anchor zone width, a 12 mm reseal zone width, and a 12.7 mm wide grip strip. Note that the reduction in the WAZ is observed to be curl in direction up opposite from the adhesive coated side (i.e. curling away from the surface the tape is applied to). Each tape is rated on a scale of Pass Plus (P+), Pass (P) and Pass minus (P−) or complete failure (F) as defined below: [0060] 1. P+: Good adhesion to the package film—peel force of 150 grams/inch and higher peel after 1 minute dwell (applied to the package film), [0061] 2. P: Moderate adhesion to the package film peel of 75-150 grams/inch after a 1 minute dwell (applied to the package film) [0062] 3. P−: Low but acceptable Adhesion to the package film peel of 75 grams-40 grams/inch after a 1 minute dwell (applied to the package film) [0063] 4. Failure F: Very light adhesion to the package film; like a 3M post it note peel of less than 40 grams/inch after a 1 minute dwell (applied to the package film), Tape fracture/break, Package film destruct, full adhesive transfer to the packaging film from the tape.

[0064] The failure mode of the PSA tape should be an adhesive failure, more specifically, a clean peel of the tape from the package where no adhesive is transferred to the package film. The subjective peel ratings are defined based on previous package testing results from industry testing.

[0065] The tapes were applied after a continuous slit was introduced to the packaging film in the direction that the film travels (machine direction) as shown in FIG. 5. The package measured 8 in. in the machine direction and a 5 in. in the cross width direction. The packages underwent 5 peel-reseal cycles at room temperature conditions (22° C./50% relative humidity per ASTM peel method specifications). The peel force was measured using an SP-2100 Slip Peel Tester from Imass Inc., Accord, Mass. The cycling followed these steps: [0066] Cycle 1—peel back the reseal strip from a new package; re-adhere the strip over the slit; wait 1 hour; measure WRZ; [0067] Cycle 2—peel back and re-adhere the reseal strip immediately after completion of cycle 1; wait 24 hours; measure WRZ; [0068] Cycle 3-5—peel back and re-adhere the reseal strip immediately after completion of the previous cycle; wait 72 hours; measure WRZ.
The results are shown in Table 6.

TABLE-US-00007 TABLE 6 Tape 1 Tape 2 Test Cycle Grade - Length of WRZ Grade - Length of WRZ Initial closure Pass (P) - 12 mm Pass (P) - 12 mm width W of reseal zone Reseal Cycle 1 Pass Minus (P−) - 6.5 mm Pass (P) -11 mm Reseal Cycle 2 Pass Minus (P−) - 3 mm Pass (P) - 8 mm Reseal Cycle 3 Fail (ultra low adhesion) - 0.5 Pass Minus (P−) - 6.5 mm mm Reseal Cycle 4 Fail (ultra low adhesion - 0.4 Pass Minus (P−) - 6.0 mm mm Reseal Cycle 5 Fail (ultra low adhesion) - 0.4 Pass Minus (P−) - 6.0 mm mm

[0069] Table 6 shows an increasing loss of adhesion (contact amount) for both tapes after each cycle, which is primarily caused when the film curls and peels away from the surface of the packaging film. In the first three cycles, degradation of the adhesive is not believed to significantly degrade adhesion.

[0070] Table 6 shows that the amount of curl and adhesion reduction of Tape 2 is small enough to make the package acceptable as a resealable consumer package. The amount of curl and adhesion reduction of Tape 1 is unacceptable as a resealable consumer package. The overall performance of each tape could be further improved by corona or flame treatment, or coating of the packaging film surface to raise the surface tension from that of untreated polyethylene 30-32 dynes/cm to greater than 36 dynes/cm but a broad range of surface treatments are common in the packaging industry and the benchmarking of an untreated surface film demonstrates the invention with its preferred properties.

[0071] Table 6 also shows how the amount of strain-induced curl reduces dramatically after the third cycle. After the third cycle, subsequent cycles induce very little strain-induced curl. Therefore, any further reduction in adhesion is more likely associated with a degradation of the adhesive.

[0072] In a preferred embodiment, the reduction in the width of the reseal zone after the first cycle is preferably less than 15%, after the second cycle is preferably less than 35%, and after the third cycle is preferably less than 50%. Preferably, the reduction in the width of the reseal zone remains less than 50% in any subsequent cycles.

[0073] In the embodiment shown in FIGS. 1-2, the PSA reseal tape 12 is constructed and arranged to “reseal” the slit when the consumer presses the tape down over the slit. When properly re-adhered, the package will not leak through the slit over an extended period of time. In another preferred embodiment, a PSA tape is constructed and arranged to “reclose” the package when the consumer folds or rolls the open end of the package and re-adheres the PSA tape over the folded or rolled end of the package to keep the package from unfolding or unrolling. In this embodiment, the fold or roll retards air exchange to the package interior, and retards spillage and contamination. However, it is not a hermetic/tight seal against leaking or spoilage due to compromise from the original, interior packaging conditions.

[0074] A preferred embodiment of the invention having a reclosable opening is shown in FIGS. 7-10 and is designated generally by reference numeral 110. In this embodiment, a PSA reclose tape is applied along the length-wise (and machine direction) dimension of the package. The package 110 has a conventional construction and was formed on an FFS machine by folding flexible packaging film into a tube with lateral edges of the film being heat welded along a longitudinal seam 114 at the rear of the package 110. Heat seal welds 114, 115 at the top and bottom, respectively, of the package complete its construction.

[0075] Referring to FIGS. 7 and 8, the package 110 has a PSA reclose tape 12 extending from the top seal 124 to the bottom seal 125. The reclose tape may be shorter than this length so long as it provides sufficient length to close the bag as described below. The reclose tape 12 preferably has the same construction as the reseal tape described above including a base material 23, a pressure-sensitive adhesive 25, and a grip strip 27.

[0076] A preferred method of reclosing a package is shown in FIGS. 9-10. Referring to FIG. 9, the reclose tape is first released from the package by grasping the grip strip near the top of the package and pulling it away from the package. Referring to FIG. 10, only portion of the reclose strip should be released from the package and a sufficient length should remain adhered to the bottom portion of the package. The top of the package is then folded down or rolled down as shown in FIG. 10. The released portion of the reclose tape is then re-adhered to the folded or rolled portion. The next time it is desired to remove some of the contents of the package, the reclose strip is peeled down again so that the top of the package may be unrolled to dispense its contents.

[0077] A machine for producing a package in accordance with a preferred embodiment of the invention is schematically illustrated in FIG. 11. In this embodiment, a roll 41 of PSA tape 12 as described above is fed into an applicator 45, which cuts and applies a predetermined length of the PSA tape 12 onto a film of packaging material 42. The film 42 then travels through a series of additional processing stations 44 and 46. From there, the film travels to further forming stations including, for example, a form-fill-seal machine (“FFS”), thereby producing the flexible packaging such as described in the Forman patents.

[0078] The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described herein, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. For example, novel resealable package can be achieved by applying a label instead of a tape. It would use a different applicator set up but one could achieve a very similar resealable package.