Patent Publication Number: US-9428307-B2

Title: Adhesive reclosable fasteners with visual indicators

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national phase application of International Application No. PCT/US2014/021084, filed Mar. 6, 2014, which claims benefit from U.S. Application 61/793,341, filed Mar. 15, 2013, which are hereby incorporated herein by reference in their entirety. 
    
    
     FIELD 
     This disclosure relates generally to reclosable fasteners for flexible packages and, in particular, to adhesive-based reclosable fasteners with open/close visual indicators for flexible packages. 
     BACKGROUND 
     Several types of closures or fasteners are available for reclosing a previously opened flexible package. For example, it is common to use mechanical reclosable fasteners, such as slider zippers, clips, tabs, interlocking strips, and the like. Such mechanical closures can have colored and/or uncolored interlocking components that can both reclose a package and indicate to a user that the package has been reclosed. Such mechanical closures can be expensive, bulky, complex structures that require separate molding and fabrication steps prior to being joined to the flexible film used to form the package. In addition, while mechanical closures can be applied in form-fill-seal operations, the mechanical closures often require complex and expensive manufacturing steps to apply, interconnect, and align the mechanical fastening features of each structure. Therefore, mechanical reclosable fasteners often add undue complexity and cost to the manufacturing process of the flexible packages. 
     Adhesive-based reclosable fasteners provide one alternative to the mechanical fasteners. For example, thermoplastic elastomers, which are sometimes called thermoplastic rubber, have been used to form reclosable pressure sensitive adhesive type fasteners. Some types of thermoplastic elastomer copolymers (especially certain styrenic block polymers) demonstrate high cohesive properties, and at the same time have low tack levels or a reduced tendency to adhere to unlike materials (i.e., food materials such as cookies, crackers, shredded cheese and the like). Such adhesive-based reclosable fasteners typically include adhesive material, typically in the form of strips, formed opposite one another on interior surfaces of the side walls of the packages. One draw-back of the known adhesive-based reclosable fasteners is that they do not typically provide an indicator to tell the consumer whether the package has been properly or improperly closed or reclosed. While some adhesive-based reclosable fasteners include color-changing indicators, such color-changing indicators may be ineffective for some users because the color change is not readily apparent, and for other users because they happen to be color-blind. Further, production of such color-changing adhesive-based reclosable fasteners adds complexity and cost to the flexible packaging manufacture. 
     SUMMARY 
     In one approach, a flexible package comprises a top end, a bottom end, a first side edge, a second side edge opposite the first side edge, a front panel, and a rear panel joined together to form an interior therebetween configured to retain a product. The package further includes a first layer of adhesive material disposed on an interior surface of the rear panel. The adhesive material of the first layer includes at least one visual indicator formed by at least one area of predetermined shape that is more translucent than adjacent areas of the adhesive material of the first layer. The package also includes a second layer of adhesive material disposed on an interior surface of the front panel. The second layer of adhesive material is positioned opposite the first layer of adhesive material to permit the flexible package to be sealed when the first layer of adhesive material and the second layer of adhesive material are brought into contact with each other. When the flexible package is not sealed, the at least one visual indicator in the adhesive material of the first layer is not visible through the adhesive material of the second layer, and when the flexible package is sealed, the at least one visual indicator is visible through the second layer of adhesive material. 
     The first layer and second layers of adhesive material may be in a form of at least one strip extending from the first side edge to the second side edge of the flexible package. 
     The shape of the at least one visual indicator can be one of a geometric shape selected from one of circular, rectangular, triangular, and polygonal, and a calligraphic shape selected from one of single words and phrases. 
     The adhesive material of the first and second layers of adhesive material may be partially opaque or translucent and may include a colorant in an amount of approximately from about 0.1 percent to about 4 percent by weight. The colorant may be selected from one of titanium dioxide, calcium carbonate, talc, or any of a variety of organic of inorganic colorants, either alone, or in combinations. 
     The first and second layers of adhesive material may each have a thickness of approximately from about 0.0001 to about 0.005 inches. 
     The first layer of adhesive material may be partially opaque except for the at least one area that is more translucent than adjacent areas of the adhesive material and forms the at least one visual indicator, and the second layer of adhesive material is partially opaque or uniformly translucent. 
     In one approach, a method of manufacturing the flexible package described herein comprises applying the first layer of adhesive material including the at least one area of predetermined shape to a portion of the interior surface of the rear panel of the flexible package, and applying the second layer of adhesive material to a portion of the interior surface of the front panel of the flexible package opposite the portion of the interior surface of the rear panel of the flexible package. 
     The method may include bringing the front panel and the rear panel of the flexible package toward each other until the first layer of adhesive material comes into contact with the second layer of adhesive material and the flexible package is sealed. 
     The method may also include applying the second layer of adhesive material to the portion of the interior surface of the front panel of the flexible package continuously from the first side edge of the flexible package to the second side edge of the flexible package. 
     The method can also include applying the first layer to the portion of the interior surface of the rear panel of the flexible package continuously from the first side edge of the flexible package to the second side edge of the flexible package. 
     In one form, the first and second layers of adhesive material each include a colorant in an amount of approximately from about 0.1 percent to about 4 percent by weight. 
     In one approach, a method of reclosing the flexible package described herein comprises bringing the front panel and the rear panel of the flexible package toward each other until the first layer of adhesive material comes into contact with the second layer of adhesive material and the at least one visual indicator in the first layer of adhesive material is visible through the second layer of adhesive material. 
     In one approach, a flexible package including a reclosable fastener comprises a top end, a bottom end, a first side edge, a second side edge opposite the first side edge, a front panel, a rear panel joined together to form an interior therebetween configured to retain a product, and a reclosable fastener. The reclosable fastener includes a first strip of adhesive material disposed on an interior surface of the rear panel such that the adhesive material of the first strip has a first translucence level and including at least one area forming a visual indicator and being more translucent than adjacent portions of the first strip of the adhesive material. The reclosable fastener also includes a second strip of adhesive material disposed on an interior surface of the front panel such that the adhesive material of the second strip has a second translucence level. The second strip of adhesive material is positioned opposite the first strip of adhesive material to permit the flexible package to be sealed when the first strip of adhesive material and the second strip of adhesive material are brought into contact with each other. When the flexible package is sealed, the reclosable fastener has a third translucence level in portions where the first strip of adhesive material is in contact with the second strip of adhesive material and a fourth translucence level where the at least one visual indicator is in contact with the second strip of adhesive material, the fourth translucence level being about 25-75% more translucent than the third translucence level such that the at least one visual indicator is visible through the second strip of adhesive material. 
     The first and second strips of adhesive material may each extend from the first side edge to the second side edge of the flexible package. 
     The at least one visual indicator can have a shape that is one of a geometric shape selected from one of circular, rectangular, triangular, and polygonal, and a calligraphic shape selected from one of single words and phrases. 
     The adhesive material of the first and second strips may include a colorant in an amount of approximately from 0.1 percent to 4 percent by weight. 
     In one form, the first translucence level can be equal to the second translucence level. When the flexible package is not sealed, the at least one visual indicator in the adhesive material of the first layer may not be visible through the adhesive material of the second layer. In an approach, neither the first strip of adhesive material nor the second strip of adhesive material changes color when the first and second strips of adhesive material are brought into contact with each other to seal the package. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of an exemplary package with an intact top end seal and having a cohesive-based reclosable fastener illustrated in a properly sealed condition; 
         FIG. 2  is a front perspective view of the package of  FIG. 1  illustrated in the properly sealed condition but with the top end seal having been removed; 
         FIG. 3  is a rear perspective view of the package of  FIG. 1  illustrated with the top end seal having been removed and in an open condition; 
         FIG. 4  is a side elevational view in cross-section of the package of  FIG. 1  illustrated in the open condition; 
         FIG. 5  is a side elevational view in cross-section of the package of  FIG. 1  illustrated in the properly sealed condition; 
         FIG. 6  is a front perspective view of the package of  FIG. 2  illustrated in an improperly sealed condition; 
         FIG. 7  is a top plan view of film rollstock that can be used to form an exemplary package including an adhesive fastener having visual indicators; and 
         FIG. 8  is a perspective view of relevant portions of a vertical form-fill-seal process for forming an exemplary package from the film rollstock as shown in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Generally, an adhesive fastener system of reclosable fastener including visual indicators having a variable opacity for flexible packages is provided. The adhesive fastener is an adhesive or cohesive material located on one or both of interior surfaces of the package that is sufficiently sticky to close the package and capable of multiple openings and reclosings. The system can include one or more strips or layers of adhesive coatings or applications on each of the front and rear panels forming walls of the package. In one approach, the adhesive on one of the walls can include one or more zones of predetermined patterns and shapes that are more translucent than the adjacent portions of the adhesive coatings. The shapes can be simple geometric figures, for example, circles, squares, triangles, or the like, or letters that form words and phases such as “CLOSED,” “SAFETY SEAL,” “FRESHNESS SEAL,” or the like. Due to the contrasting translucence of coated and uncoated zones of the adhesive strips, the uncoated zones provide for a variable translucence or change in degree of translucence leading to a visual appearance change of the package when the two opposing adhesive strips are joined together to close or reclose the package, indicating to a user whether the package is properly sealed. 
     For purposes of this application, the terms “translucence” and “translucent” will be understood as the property of a material allowing at least some incident light to pass through while the transmitted light can be scattered; the term “light scattering” will be understood as a deflection of a ray of light from a straight path, for example by irregularities in the propagation medium, particles, or in the interface between two media; the terms “opaque” and “opacity” will be understood as the property of not allowing transmission of light; the terms “transparent” and “transparency” will be understood as the property of a material allowing light to pass through without being scattered; and the term “partially opaque” will be understood as the property of a material whereby some incident light is not transmitted, i.e., either absorbed or reflected. 
     In one approach, a flexible package  10  having an adhesive-based reclosable fastener  12  with visual indicators  13 ,  15  is disclosed herein and generally illustrated in  FIGS. 1 to 6 .  FIGS. 1, 2, and 5  illustrate the package  10  being in a fully sealed or closed condition and  FIGS. 3, 4, and 6  illustrate the package  10  that is not in a fully sealed or closed condition. In one exemplary form, the package  10  is formed from a flexible sheet material or film and includes a front flexible panel or wall  16  and rear flexible panel or wall  18 . The package also includes a first side edge  20  and a second side edge  22  opposite the first side edge  20 . The first and second side edges  20  and  22  of the package  10  each may include an end seal or a dead fold. The package further includes a bottom end  24  and a top end  26  opposite the bottom end  24 . The front and rear walls  16  and  18 , opposite side edges  20  and  22 , and bottom and top ends  24  and  26  are joined together to form the flexible package  10  having an interior  28  (shown, for example in  FIG. 5 ) for containing a food item or other products. The food item may be, for example, candy, cookies, nuts, crackers, or the like. The exemplary package is shown as being rectangular, but may have other shapes, sizes, and orientation as needed for particular applications. 
     With reference to  FIG. 1 , the bottom end  24  of the package  10  includes a bottom end seal  25  and the top end  26  of the package  10  includes a top seal  27 . In one approach, the top end seal  27  may be separated from the package  10  along a line of weakness  29 . The line of weakness  29  can be a score line, which, in one approach, can be scribed with one or more lasers in the flexible film material from which the package  10  is made. For example, a carbon dioxide laser or another suitable laser may be used to scribe the score line  29  in the front and rear side walls  16  and  18  of the package  10 . In one approach, the package  10  may include a tear notch (not shown) aligned with the line of weakness  29 . 
     The top end seal  27  provides a tamper-evident feature for the package  10  such that the absence of, or the partial removal of the top end seal  27  would indicate to a consumer that the package  10  has been previously opened or tampered with. Removal of the top end seal  27  provides an access opening  31  for accessing the hollow interior  28  as well as dispensing the contents of the package  10 . The package  10  may further include other folds, seals, gussets, and/or flaps as generally needed for a particular application. For instance, as shown in  FIG. 1 , the package  10  may also include one or more fin seals  33  extending longitudinally from the top end  26  to the bottom end  24  of the package  10 . 
     Referring to  FIGS. 3 and 4 , the reclosable fastener  12  includes a first layer or strip of adhesive material  30  on an interior surface  19  of the rear wall  18  of the package  10  and a second layer or strip of adhesive material  32  on an interior surface  17  of the front wall  16  of the package  10 . As described in more detail below, the first and second layers of adhesive material  30  and  32  are positioned opposite each other to permit the flexible package  10  to be fully sealed when the first layer of adhesive material  30  is brought into contact with the second layer of adhesive material  32 . 
     In the exemplary form shown in  FIGS. 1-3 , the first and second layers of adhesive material  30  and  32  are in the form of strips that run from the first side edge  20  to the second side edge  22  of the package  10 , and are generally aligned with each other such that facing inner surfaces  34  and  36  of each fastener layer  30  and  32  oppose each other and are positioned to engage each other to form a closed or fully sealed condition of the package  10 , shown, for example, in  FIG. 5 . As shown in  FIG. 5 , the inner-facing surfaces  34  and  36  of the first and second layers of adhesive material  30  and  32  are substantially parallel to each other when the package is in the sealed condition. While the reclosable fastener  12  has been shown by way of example only as being formed from first and second layers of adhesive material  30  and  32  in the form of generally parallel strips that continuously extend from the first side edge  20  to the second side edge  22  of the package  10 , it will be appreciated that the reclosable fastener  12  may be formed in any suitable shape. In addition, the adhesive layers  30  and  32  do not have to be continuous from the first side  20  to the second side  22  and can extend across only a portion of the distance from the first side edge  20  to the second side edge  22  of the package  10 . 
     In one approach, the first and second layers of adhesive material  30  and  32  of the fastener  12  are in the form of, for instance, a thin radiation-curable adhesive coating or layer which is normally transparent. In some cases, to make the fastener  12  more visible to a consumer, the first and second layers of adhesive material  30  and  32  may include a low concentration (in one approach, about 0.1 to about 4% by weight, in another approach, about 1 to about 4% by weight, in yet another approach, about 2 to about 3% by weight) of a pigment or colorant in order to provide some opacity to the adhesive. In one approach, titanium dioxide, calcium carbonate, or talc may be the pigment included in the first and second layers of adhesive material  30  and  32 . The presence of pigment in the first and second layers of adhesive material  30  and  32  makes the layers  30  and  32  partially opaque, and therefore, more visible to the human eye than the transparent side walls  16  and  18  of the package  10 . 
     In the approach depicted in  FIG. 3 , the first layer of adhesive material  30  extends continuously from the first side edge  20  to the second side edge  22  of the package  10 . The first layer of adhesive material  30  is in the form of a strip that has a degree of opacity or translucence level such that it is partially opaque (i.e., translucent but not transparent) due to the presence of a colorant therein, as described above. As shown in  FIG. 3 , the strip forming the first layer of adhesive material  30  includes one or more, and as illustrated in the exemplary form, two areas, zones, or portions  13  and  15  that in one approach, include a thinner layer of adhesive material  30  than adjacent areas of the first layer of adhesive material  30 , and in another approach, uncoated with adhesive material. As used herein, uncoated with adhesive material generally means free of, in the absence of, or no adhesive. The areas of the fastener  12  that form the visual indicators  13  and  15 , whether they have a thinner layer of adhesive material  30  than adjacent areas of the first layer of adhesive material  30 , or uncoated with adhesive material, are more translucent than adjacent areas of the first layer of adhesive material  30 . In one approach, the areas  13  and  15  are transparent. 
     As discussed below, the areas  13  and  15  serve as visual indicators that can provide a consumer with information as to whether the package  10  has been properly sealed or not. As depicted in  FIG. 3 , the second layer of adhesive material  32  does not have visual indicators such as  13  and  15  and has an opacity level such that it is entirely partially opaque or uniformly translucent and extends continuously from the first side edge  20  to the second side edge  22  of the package  10 . It is to be appreciated that the visual indicators  13  and  15  are not restricted to being present in only one of the first and second layers of adhesive material  30 ,  32  as shown in  FIG. 3 . For example, in one alternative approach, the second layer of adhesive material  32  may also include two visual indicators  13  and  15 , such that both the first layer of adhesive material  30  and the second layer of adhesive material  32  each include one or more visual indicators  13 ,  15 . In one form, the visual indicators  13 ,  15  of the first layer of adhesive material  30  are offset from the visual indicators  13 ,  15  of the second layer of adhesive material  32 , facilitating a user in determining whether the package  10  is properly sealed from either the front or the rear of the package, i.e., by looking at the front wall  16  of the package  10 , or the rear wall  18  of the package  10 . It is to be appreciated that while two visual indicators  13  and  15  have been illustrated in the first layer of adhesive material  30  in  FIGS. 1-3 , and two visual indicators  13  and  15  can be in the second layer of adhesive material  32 , it will be appreciated that the each of the first and second layers of adhesive material  30 ,  32  of the fastener  12  of the package  10  can include only one, three, four, five, or more such indicators as needed for a particular application to indicate that the package  10  is properly closed. It will also be appreciated that the opacity level of the second adhesive layer  32  may be the same as the opacity level of the first adhesive layer  30  (not counting the visual indicator zones  13  and  15 ). Alternatively, the opacity level of the first and second adhesive layers  30  and  32  may be different. 
     As shown in the exemplary form of  FIGS. 1-3 , the uncoated zones  13  and  15  in the first layer of adhesive material  30  are shaped in the form of circles. The visual indicators  13  and  15  have been illustrated as circles by way of example only, and it will be appreciated that the visual indicators  13  and  15  can have any shape and pattern. For example only, the visual indicators  13  and  15  may be in the form of simple geometric figures and shapes (for example, triangles, rectangles, squares, other polygons, straight lines, curved lines, and/or undulating lines, as well as irregular shapes) or letters (for example, “SAFETY SEAL,” “FRESHNESS SEAL,” or the like). In addition, the fastener  12  may have a plurality of identical visual indicators, or may have two or more visual indicators that are different from one another. 
     The reclosable fastener  12  generally has an adhesive bond strength to permit the opposing first and second layers of adhesive material  30  and  32  to be bonded together in order to close or seal the package  10 . For example, when the package  10  is open as shown in  FIG. 4 , a consumer may reclose the package  10  by pressing the opposing first and second adhesive layers  30  and  32  toward each other and into engagement to fully seal or close the package  10 . By one approach, the bond between first and second adhesive layers  30  and  32  is generally sufficient to seal the first and second adhesive layers  30  and  32  together and, preferably, form a hermetic seal. As used herein, hermetic is understood to mean a generally air tight seal, for example, no bubbles are visible in standard bubble emission leak test ASTM D 3078-02. In one example, the selected material forming the first and second adhesive layers  30  and  32  may exhibit a cohesive or peel bond strength between layers  30  and  32  of about 100 to about 700 g/inch, and in some cases, between about 100 to about 400 g/inch as measured by the ASTM peel test D 3330-Method F; however, the reclosable fastener  12  may have other peel strength values dependent on the particular application or particular measurement test. 
     As shown in  FIG. 6 , when the first and second layers of adhesive material  30  and  32  are not in contact (i.e., when the package  10  is not sealed), the opacity level of the second layer of adhesive material  32  is such that the first layer of adhesive material  30  is not visible when viewed directly through the second layer of adhesive material  32 . Specifically, when the package  10  is not completely sealed or in an open position shown in  FIGS. 4 and 6  such that the layers  30  and  32  are not in contact with each other and viewed by a consumer from the side of the front wall  16  along an axis  35  (shown in  FIG. 4 ) representing the consumer&#39;s line of sight, the second layer of adhesive material  32 , which is a continuous partially opaque coating, scatters and/or absorbs some of the incident light and obstructs the consumer&#39;s view of the visual indicators  13  and  15  in the first layer of adhesive material  30 . 
     Conversely, when the package  10  is in the fully sealed condition shown in  FIGS. 2 and 5 , the total translucence level of the package  10  in the region of the fastener  12  is equal to the combined translucence levels of the first and second layers of adhesive material  30  and  32 , except in the locations of the zones (not fully coated with, having a thinner layer of, or lacking adhesive material) representing the visual indicators  13  and  15 . In the zones that represent the visual indicators  13  and  15 , the translucence level of the fastener  12  is, in one approach, twice as great as the translucence level across the rest of the area representing the fastener  12 . In other words, the opacity level of the package  10  in the region of the fastener  12  is, in one approach twice as great in the regions where two layers of adhesive material (i.e., the first and second layers  30  and  32 ) are present as compared to the regions where only one adhesive layer (i.e., the second layer  32 ) is present. As such, when the first and second layers of adhesive material  30  and  32  are in contact with each other, contact clarity results in the region of the fastener  12  such that the visual indicators  13  and  15  can be visible by the consumer through the second layer of adhesive material  32  along the line of sight or axis  35 . It is to be appreciated that the areas of the fastener  12  where the visual indicators  13  and  15  are present may be more than or less than 50% more translucent (e.g., from about 25% to about 75%) than the remaining areas of the adhesive material across the fastener  12 . The opacity level of the fastener  12  may be varied as needed by the thickness of the adhesive coating and/or the amount of colorant. For example, in alternative approaches, layers  30  and  32  of the fastener  12  may each be a different thickness and/or may each have a different amount of colorant. 
     The variation in the visibility of the visual indicators  13  and  15  through the second layer of adhesive material  32  between the open and closed conditions of the front and back walls  16  and  18  of the package  10  advantageously provides visual indication to a consumer regarding whether the package  10  is open or closed without the use of strips that change colors when moved from an open to a closed position and without the use of interlocking members that look different when open or closed. For example, neither the first adhesive layer  30  nor the second adhesive layer  32  of the package  10  changes colors when the package  10  is moved from an open condition to a closed condition. Instead, when the second adhesive layer  32  is in contact with the first adhesive layer  30  during the closed condition of the package  10 , the fastener  12  is visibly more translucent in the areas where the visual indicators  13  and  15  are present and the second adhesive layer  32  does not change color but appears less opaque or more translucent opposite the areas where the visual indicators  13  and  15  are present. In other words, when the two adhesive layers  30  and  32  are joined, the pattern of contrasting opacity level caused by the presence of the visual indicators  13  and  15  becomes visible from the perspective of a consumer looking at the package  10  through the front panel. 
     As shown in  FIG. 2 , the portions of the fastener  12  where the more translucent or transparent zones representing the visual indicators  13  and  15  in the first layer of adhesive material  30  are in contact with the partially opaque second layer of adhesive material  32  appear as being more translucent or less opaque compared to the appearance of the portions of the fastener  12  where the partially opaque portions of the first adhesive layer  32  are in contact with the partially opaque second adhesive layer  32 . As such, the ability of the consumer to see the shape represented by the visual indicators  13  and  15  provides a consumer with a confirmation that the package  10  has been fully sealed or reclosed. Conversely, the consumer&#39;s inability to see the shapes formed by the visual indicators  13  and  15  directly through the adhesive layer  32  is an indication that the package  10  has not been fully sealed because there is still a gap  31  between the first and second layers of adhesive material  30  and  32 , as shown in  FIG. 4 . Accordingly, the visual indicators  13  and  15  advantageously provide the consumer with easily discernable information as to whether the package  10  has been properly or improperly sealed. 
     In one aspect, the fastener  12  may be a cohesive-based reclosable fastener generally constructed or have a composition adapted to minimize the adhesion of the fastener  12  to undesired surfaces and still function at the same time as an effective reclosable fastener. That is, the fastener  12  can be opened and closed multiple times to seal food products or other products in the interior  28  of the package  10  during use by a consumer, but at the same time not delaminate from the front and back walls  16  and  18  that form the side walls of the package  10 . In one approach, the adhesive-based reclosable fastener  12 , which has a strong bond to the front and back walls  16  and  18  of the package  10 , includes an adhesive having relatively low tack levels to minimize adhesion to the unwanted surfaces such as food crumbs or cheese shreds, but with a bonding or opening peel strength sufficient to enable sealing or reclosure of the package  10  and permit unbonding to allow opening and/or re-opening of the package  10 . 
     In one form, the material forming the package  10  can be a flexible sheet material or film, which may be formed of various plastic polymers, co-polymers, papers, or foils. The film substrate may be a multi-layer coextrusion and/or a laminate with constructions to enhance interfacial bonding with the energy-cured patterned adhesive fastener  12 . In general, the polymeric layers may include polyolefins such as polyethylene (high, medium, low, linear low, and/or ultra low density polymers including metallocene or polypropylene (oriented and/or biaxially oriented)); polybutylene; ethylene vinyl acetate (EVA); polyamides such as nylon; polyethylene terephthalate; polyvinyl chloride; ethylene vinyl alcohol (EVOH); polyvinylidene chloride (PVDC); polyvinyl alcohol (PVOH); polystyrene; or combinations thereof, in monolayer or multi-layer combinations. In one aspect, the material forming the package  10  includes EVA. Examples of suitable material from which the flexible package  10  can be formed may be found in U.S. Publication Nos. 2008/0131636, 2008/0118688, and 2011/0211778, incorporated herein in their entirety. Other materials may also be used for the flexible package. 
     The first and second layers of adhesive material  30  and  32  of the fastener  12  can be formed from various suitable adhesive materials and can be provided in the form of a solution consisting of a thermoplastic elastomer diluted with an ethylene vinyl acetate copolymer in an organic solvent or mixture of organic solvents. The fastener  12  may be also formed from a UV-curable acrylic adhesive. Materials suitable for the fastener  12  are described, for example, in U.S. Publication Nos. 2009/0279813 and 2011/0211778, both incorporated by reference herein. By one approach, a suitable flexible film that can form the front and rear walls  16  and  18  of the package  10  may be a polyethylene-based film having a thickness of, in one approach, about 0.0005 to about 0.005 inches, in another approach, about 0.001 to about 0.005 inches, in another approach, from about 0.025 to about 0.005 inches. By way of example only, the first and second layers of adhesive material  30  and  32  of the fastener  12  can have a thickness of approximately from about 0.0001 to about 0.005 inches, in another approach, about 0.0005 to about 0.001 inches, in another approach, from about 0.001 to about 0.005 inches. In one form, the area of the first adhesive layer  30  forming the visual indicator  13  extends across the entire thickness of the first adhesive layer  30 , as depicted in  FIG. 4 . It will be appreciated that the area forming the visual indicator  13  can extend across less than the entire thickness of the first adhesive layer  30 . 
     In one approach, the materials forming the first and second adhesive layers  30  and  32  have a relatively low tack level that limits the adhesion of the fastener  12  to unwanted materials and surfaces, such as food particles, forming equipment surfaces, rollers, and the like. By one approach, the selected adhesive materials may have a tack level to undesired surfaces of not exceeding about 5 psi when preloaded with about 4.5 pounds and generally not exceeding about 15 psi when preloaded with about 10 pounds using the ASTM probe tack test D 2979; however, the tack level may also vary depending on the particular cohesive material chosen, application thereof and measurement test used. 
     A suitable method of manufacturing the flexible package  10  including the first and 
     second layers of adhesive material  30  and  32  is described with reference to  FIGS. 7 and 8  below, and can comprise (1) applying the first layer of adhesive material  30  including at least one area  13  and  15  of predetermined shape to a portion of the interior surface  34  of the rear panel  18  of the flexible package  10 ; and (2) applying the second layer of adhesive material  32  to a portion of the interior surface  36  of the front panel  18  of the flexible package  10  opposite the portion of the interior surface  34  of the rear panel  18  of the flexible package  10 . In one approach, after the application of the first and second layers of adhesive material, which may include titanium oxide, calcium carbonate, talc, or the like in an amount of approximately from 0.1 percent to 4 percent by weight, the first and second layers of adhesive material  30  and  32  are cured at a curing station. For example, the first and second layers of adhesive material  30  and  32  may be energy cured, such as UV-cured and/or E-beam cured. An exemplary method suitable for applying the first and second layers of adhesive material  30  and  32  to the front and rear walls  16  and  18 , respectively, of the package  10  is described in 2011/0211778, which is incorporated by reference herein. The package  10  can be manufactured from a single sheet or web of flexible material  100 . The flexible material  100  may be a film made of one or more plastic polymers, co-polymers, unmetalized or metalized laminates, paper, or the like. A portion of an exemplary web of the flexible film  100  is depicted in  FIG. 7 . In the approach illustrated in  FIG. 7 , the exemplary web of the flexible film  100  includes multiple areas or strips  112  that correspond to the fastener  12  in the formed flexible package  10 . Specifically, the exemplary strips  112  include areas  131  coated with adhesive material that correspond to the first and second layers of adhesive material  30  and  32  of the formed flexible package  10 . The exemplary strips  112  also include areas  113 ,  115  either lacking or having a thinner coating of the adhesive material that correspond to the visual indicators  13  and  15  of the formed package  10 . It is to be appreciated that while the exemplary strips  112  have been shown in  FIG. 7  in the form of a single continuous strip, each of the strips  112  may be in the form of two or more discontinuous or spaced apart strips, or strip-like areas. It is also to be appreciated that while the fastener  12  of the package  10  of  FIG. 1  is shown with two visual indicators  13 ,  15 , each strip  112  (that will form the fastener  212  of the package  200 ) depicted in  FIG. 7  includes two sets of three visual indicators  113 ,  115 , resulting in a total of six visual indicators. 
     As the flexible film  100  moves in the machine direction shown by the directional arrow in  FIG. 8 , the film  100  includes a plurality of adhesive strips  112  described above. The strips  112  can be applied to, or made in the flexible film  100  before or after the flexible film  100  is unwound from the feed roll  101  in the machine direction. Prior to, or after disposing the strips  112  on the flexible film  100 , lines of weakness  129  are formed in the flexible film  100  above the strips  112 , as shown in  FIG. 8 . The lines of weakness  129  can be formed in the flexible film  100  using, for example, laser ablation, die-cutting, micro-abrasion, or other suitable means. The lines of weakness  129  in the flexible film  100  correspond to the line of weakness  29  and  229  of the exemplary packages  10  and  200 , respectively. 
     As the flexible film  100  moved in the machine direction and along a vertical form-fill-seal device  103 , the opposite longitudinal edges  102  and  104  of the flexible film  100  are folded inward such that both the longitudinal edges  102  and  104  of the flexible film  100  and the visual indicators  113  and  115  are brought toward each other as shown in  FIG. 8 , and a product  90  (e.g., a food product such as candy, chocolates, nuts, or the like, or another consumer product that is not a food product) is deposited into the vertical form-fill-seal device  103  such that the flexible film  100  envelopes the product  90 . As shown in  FIG. 8 , sealing jaws  118  seal the longitudinal edges  102 ,  104  of the flexible film  100  together to form an area  133  which corresponds to a fin seal  33 ,  233  of the formed package  10  and  200 , respectively. Finally, a cutting device such as cutting jaws  120  and  122  make one or more cuts though the flexible film  100  to singulate the individual exemplary package  200  as shown in  FIG. 8 . 
     The package  200  is substantially similar to the package  10  of  FIGS. 1-6 , but the fastener  212  of the package  200  includes two sets of three visual indicators  113 ,  115  instead of two visual indicators  13  and  15  as provided in the fastener  12  of the package  10 . It will be appreciated that the number of visual indicators provided in the fasteners  12  and  212  have been chosen by way of example only, and that the number of visual indicators can be increased or decreased to suit a particular size and/or use of a package. For ease of reference, in  FIG. 8 , the aspects of the package  200  that are similar to the aspects of the package  10  have been designated with similar reference numbers, but prefaced with a “2.” 
     The exemplary flexible packages  10  and  200  described herein provide advantages over the known packages in that they includes reclosable adhesive-based fasteners  12 ,  212  including visual indicators  13 ,  15 ,  213 ,  215  having contrasting opacity and differing translucence relative to the remainder of the fasteners  12 ,  212  and that can be easily applied to the flexible film from which the packages  10 ,  200  are formed during the manufacturing process. The visual indicators  13 ,  213  and  15 ,  215  of the fasteners  12 ,  212  do not rely on color changes in their operation and are easily observable even by people who are color-blind, unlike various color-changing visual indicators. To this end, in one approach, the difference in the opacity level of the reclosable fastener between the open and closed conditions is not categorical, but rather a matter of degree where the opacity level observed along the reclosable fastener appears to vary without changing the color of the fastener, between the open and closed conditions of the fasteners  12 ,  212 . Finally, since the visual indicators  13 ,  213  and  15 ,  215  of the fasteners  12 ,  212  do not require any interlocking mechanical parts, the flexible packages  10 ,  200  are cheaper to manufacture than many of the presently known packages. 
     It will be understood that various changes in the details, materials, and arrangements of the package and process of formation thereof, which have been herein described and illustrated in order to explain the nature of the described package, may be made by those skilled in the art within the principle and scope of the embodied method as expressed in the appended claims.