Abstract:
A method of making a fastener product having discrete regions of fastener element stems extending from a strip-form base includes providing a gap formed along a peripheral surface of a rotating mold roll, the mold roll having a plurality of cavities exposed about the peripheral surface. A sleeve is introduced to the gap. The sleeve is positioned about the mold roll and covers selected cavities. Molten resin is introduced to the gap such that the resin forms at least a part of the strip-form base of the product at the peripheral mold roll surface and at least partially fills a plurality of the cavities to form fastener element stems as projections extending from the strip-form base, while the resin remains blocked from said selected ones by the sleeve. The resin is solidified and stripped from the peripheral surface of the mold roll by pulling the projections from their respective cavities.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation under 35 U.S.C. §120 of co-pending, US-designating PCT application US02/16898, filed May 29, 2002, which claims priority from U.S. provisional patent application 60/294,401, filed May 29, 2001. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to fastener products and methods and apparatus of their manufacture, and more particularly to forming discrete fastener element regions on such products.  
         BACKGROUND  
         [0003]    Fastener products having a base substrate with fastener elements for engagement with loops or like fastener elements can be continuously produced from, e.g., a thermoplastic material. Typically, methods for producing such fastener products result in tape-like substrates having a continuous pattern of fastener elements extending across an entire surface or in uniform bands or rows along the length of the substrate. Often times, however, it would be advantageous in applications for such fastener products, to have the presence of the fastener elements limited to pre-selected zones or arranged in patterned areas along the substrate.  
           [0004]    For example, there are some applications where it would be desirable to have patterned fastener element, e.g., hook, areas with adjacent areas that lack fastener element protrusions on a common web. Currently any such fastener products are generally made by multi-step forming, cutting and joining operations because most hook products are limited to complete or at least continuous hook coverage across or along the length of the hook bearing web. Providing hook products having other configurations would generally require specially designed tooling, e.g., hook forming mold cavity rolls with flat areas and hook forming cavity areas in the desired configuration. However, if the desired hook bearing shape and/or pattern is subsequently changed, the specialty tool would require redesign and or rebuilding to accommodate the change.  
         SUMMARY  
         [0005]    In one aspect, the invention provides a fastener product including a longitudinally extending strip-form base and a plurality of longitudinally discrete regions of fastener element stems, each discrete region including a thermoplastic resin layer bonded to a second base material by an intermingling of the resin of the resin layer with the second base material, the fastener element stems being molded, integral extensions of the resin from the resin layer, wherein each longitudinally discrete region is surrounded by an area of the strip-form base that is free of the fastener element stems.  
           [0006]    Variations of this aspect of the invention can include one or more of the following features in any combination. The second base material is a barrier layer. The second base material is a backing substrate. The area of the strip-form base that is free of the fastener element stems is covered with a barrier material. The barrier material forms a lamination barrier. The lamination barrier is one of an overprint varnish and an overprint ink. The barrier material is one of a fabric, a paper, or a film. The barrier material is a fabric with engageable loops. The fastener element stems have engaging heads. The engaging heads are molded substantially simultaneously with the fastener element stems. The engaging heads are formed by a post-molding operation.  
           [0007]    In another aspect, the invention provides a method of making a fastener product having discrete regions of fastener element stems extending from a strip-form base. The method includes: providing a gap formed along a peripheral surface of a rotating mold roll, the mold roll having a plurality of cavities exposed about the peripheral surface; introducing a barrier material to the gap, the barrier material covering selected ones of said plurality of cavities; continuously introducing molten resin to the gap such that the resin forms at least a part of the strip-form base of the product at the peripheral mold roll surface and at least partially fills a plurality of the cavities to form fastener element stems as projections extending from the strip-form base, while the resin remains blocked from said selected ones by the barrier material; solidifying the resin; and stripping the solidified resin from the peripheral surface of the mold roll by pulling the projections from their respective cavities.  
           [0008]    Variations of this aspect of the invention can include one or more of the following features in any combination. The cavities are stem-shaped, the projections extending from the strip-form base to a stem top. The method further includes a step of deforming the stem tops to form loop-engaging heads on the projections. The cavities include a loop-engaging head shape so that the projections formed from the cavities include a loop-engaging head. The barrier material is a sleeve positioned about the mold roll, the sleeve covering selected ones of the plurality of mold cavities and having an aperture (or many apertures) for exposing other cavities for the formation of a discrete region (or many discrete regions) of the fastener element stems. The barrier material is an endless belt positioned to continuously pass through the gap, the belt covering selected ones of the plurality of mold cavities and having an aperture (or many apertures in a repeating or non-repeating pattern) for exposing other cavities for the formation of one or more discrete regions of the fastener element stems. The barrier material becomes permanently bonded to the resin to form part of the strip-form base. An exposed portion of the barrier material is engageable by the engaging heads of the fastener element stems.  
           [0009]    In another aspect, the invention provides a method of making a fastener product having an array of fastener element stems protruding from a longitudinally extending strip-form base, the fastener element stems being permanently bonded to the strip-form base in only discrete regions by way of a thermoplastic resin layer that is permanently bonded to the strip form base. The method includes: continuously introducing molten resin to a gap formed along a peripheral surface of a rotating mold roll, such that the resin at least partially fills an array of fixed cavities defined in the rotating mold roll to form fastener element stems projecting from a surface of the sheet-form base; while continuously introducing a backing substrate to the molten resin while the resin is disposed in the gap, the backing material being selectively coated with a lamination barrier material to form coated areas and uncoated areas, the backing material being introduced under conditions selected to cause the material to become permanently bonded to the resin only in the uncoated areas; solidifying the resin; and stripping the solidified resin from the peripheral surface of the mold roll by pulling the fastener element stems from their respective cavities.  
           [0010]    Variations of this aspect of the invention can include on or more of the following features in any combination. The method further includes a step of cutting the solidified resin only along a transition line formed at an intersection of the coated areas and the uncoated areas while leaving the backing material intact. The method further includes a step of stripping the backing material away from unbonded solidified resin to leave discrete regions of fastener element stems permanently bonded to the backing material. The backing material is a printable cloth. The backing material is a nonwoven. The backing material is a plastic film. The lamination barrier material is one of an overprint varnish or an overprint ink. The fastener element stems are molded to have engaging heads. The method further includes a step of deforming tops of the fastener element stems to form engaging heads. The method includes leaving a portion of the unbonded regions of the backing material and the solidified resin intact to form a tab feature, wherein a separate substrate can be attached, e.g., by adhesive or otherwise, to the tab by either inserting the separate substrate between the unbonded portions of the backing material and the solidified resin, or by placing the separate substrate beneath a bonded portion of the backing substrate and folding an unbonded portion of the backing substrate to sandwich the separate substrate between bonded and unbonded portions of the backing substrate.  
           [0011]    In another aspect, the invention provides any of the fastener products produced by the methods discussed above or disclosed herein.  
           [0012]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0013]    [0013]FIG. 1 illustrates various methods and apparatus for forming a fastener product with discrete fastener element bearing regions.  
         [0014]    [0014]FIG. 2 is a sectional view of a barrier material with areas removed for use in the method and apparatus of FIG. 1.  
         [0015]    [0015]FIG. 3 is an unscaled cross sectional view of the fastener product having discrete fastener element bearing regions produced by the method and apparatus of FIG. 1.  
         [0016]    [0016]FIG. 3A is a view similar to that of FIG. 3 of an alternate fastener product.  
         [0017]    [0017]FIGS. 4 and 4A are unscaled side and cross-sectional views of a tight fitting metal sleeve with cutouts for use in an alternate method of producing fastener products having discrete hook-bearing regions.  
         [0018]    [0018]FIG. 5 is an unscaled cross sectional view of a fastener product having discrete fastener element bearing regions produced by the metal sleeve of FIGS. 4 and 4A in conjunction with certain methods paratus of FIG. 1.  
         [0019]    [0019]FIG. 6 is a sectional view of a packing film or other suitable material with discrete areas of overprint coating.  
         [0020]    [0020]FIG. 7 is a sectional view of a tab feature.  
         [0021]    [0021]FIG. 8 is a sectional view of a fastened tab feature.  
         [0022]    [0022]FIG. 9 is an end view of a method and apparatus for forming a fastener product while FIG. 9A is a magnified side view of a portion taken on lines  9 A- 9 A of FIG. 9.  
         [0023]    [0023]FIG. 10 and  10 A are, respectively, magnified, diagrammatic plan and cross-sectional views of a backing substrate having a lamination barrier.  
         [0024]    [0024]FIGS. 11-11A are, respectively, magnified, diagrammatic plan and cross-sectional views of a portion of an intermediate fastener product while FIG. 11B is a further magnified view along line  11 B of FIG. 11A.  
         [0025]    [0025]FIG. 12 is a magnified, diagrammatic plan view of a fastener product.  
         [0026]    [0026]FIGS. 13 and 14 depicts a step in forming tab products. 
     
    
     DETAILED DESCRIPTION  
       [0027]    Referring to FIGS. 1, 1A,  2  and  2 A, the invention provides various methods for forming fastener products  10  having a longitudinally extending (direction of arrow A) strip-form base  12  with longitudinally discrete fastener element bearing regions  14 . Each fastener element bearing region  14  is surrounded by an area  13  that is free of fastener elements. Fastener element bearing regions  14  can be created on fastener product  10  in a repeating or non-repeating pattern and the pre-determined shape of each can be modified as desired, in accordance with the application for which the fastener product is intended. Each fastener element bearing region  14  includes an array of fastener elements  16 , which extend from base  12 . In turn, each fastener element  16  has a stem  18  and an engaging head  20 , which is capable of engaging like or unlike fastener elements, or a loop material. Engaging head  20  is hook-shaped to overhang base  14  and to thereby provide for engagement, while in an alternate embodiment (FIG. 2A) engaging head  20 ′ is in the form of a disc-shape that overhangs base  14  to provide for engagement.  
         [0028]    Referring now to FIG. 3, various methods are illustrated for providing fastener products such as, e.g., the aforementioned product  10 . The methods build upon the continuous extrusion/roll-forming methods for molding fastener elements on an integral, sheet-form base described by Fischer in U.S. Pat. No. 4,794,028, and the nip lamination processes described in Kennedy, et al. in U.S. Pat. No. 5,260,015, the details of both of which are incorporated herein by reference. The relative positions and sizes of the rolls and other components illustrated in FIG. 1 are schematic and are not to scale. An extrusion head  30  supplies a continuous sheet of molten resin  32  to a nip  34  between a molding roll  36  and a counter rotating pressure roll  38 . Mold roll  36  contains an array of miniature, mold cavities  40  extending inward from its periphery for molding at least a portion of the fastener elements. The array of cavities  40  extends substantially about the entire periphery of mold roll  36 . Pressure in the nip  34  forces resin  32  to enter and at least partially fill the exposed mold cavities  40 , while excess resin forms a base substrate from which the fastener elements extend, as further described below. The formed product is cooled on the mold roll until the solidified fastener elements (e.g., hooks) are stripped from their fixed cavities by a stripper roll  42 .  
         [0029]    Referring now also to FIGS. 4, 4A and  4 B, in some embodiments (FIG. 4), cavities  40  of mold roll  36  have a stem forming portion  44  and an engaging head forming portion  46  so as to form stems having engaging heads during the molding process. The result, for example, can be a fastener product having molded fastener elements such as those illustrated and discussed above with reference to FIG. 2A. In these embodiments, the solidified product stripped from mold roll  36  has fastener elements capable of engagement. In other embodiments (FIG. 4A), cavities  40  of mold roll  36  have only a stem forming portion  44 ′. In these embodiments, the product  10 ′ (FIG. 4A) stripped from mold roll  36  has stems  18 ′, extending from base  12  which can be post-treated to form engaging heads. For example, after molding and stripping the product from mold roll  36 , the tops of the molded stems can be deformed by pressure and/or heat to create discs or other shapes that overhang the base of the product and are capable of engaging, e.g., loop material or like fastener elements.  
         [0030]    Referring still to FIG. 3 and now also to FIG. 5, a number of methods can be employed to prevent the formation of fastener element stems and/or fastener elements on selected areas while forming longitudinally discrete hook bearing zones or regions on other areas of the base of the fastener product. In one embodiment, a thin layer of material such as fabric or paper  50  may be fed from a roll  52  and die cut in a pattern or otherwise by a rotary die station  54  to form a barrier  56  (see FIG. 5) having apertures  58 . Barrier material  56  can then be introduced into the nip  34  between mold roll  36  and molten resin  32  thus covering selected areas of the periphery surface of mold roll  36 , and thereby shielding any mold cavities  40  corresponding to these covered areas from resin  58 , while exposing other areas of the mold roll periphery surface, which coincide with apertures  58 , to the resin. Pressure in nip  34  forces molten resin  32  into any mold roll cavities  40  that correspond with apertures  58  of barrier material  56 , while those cavities covered by barrier material  56  remain empty. Meanwhile, thermoplastic resin  32  in excess of the exposed cavity volume is bonded to one surface of the barrier material  14 . The resulting continuous fastener product  60  (see FIG. 6), like product  10  described above with reference to FIGS. 1 and 1A, has a strip-form base  12  with integrally molded, discrete zones  14  of fastener elements  16  (or, at least fastener element stems, which can be later post-formed, as described above). In the case of product  60 , base  12  is made up of a thermoplastic support layer  62 , from which the discrete zones  14  of fastener elements  16  are integrally molded to extend, the discrete zones  14  of fastener elements  16  protruding through openings  68  of a laminated barrier layer  70 .  
         [0031]    Referring again to FIG. 5, it is noted that, of course, the openings  58  cut into barrier material  56  may vary in size and shape and may be arranged in a patterned or unpatterned series to produce correspondingly shaped and patterned discrete zones of hook  14  on fastener product  60 . Barrier material  56  can be, for example, a film, paper, nonwoven, knit loop, or fabric material. In some cases, referring again to FIG.  3  and now as well to FIG. 7, barrier material  56  is engageable by the fastener elements  16 , e.g., barrier material  56  is a suitable loop material. Again, this barrier material is die cut prior to feeding it through nip  34  to provide openings, e.g., apertures  58 , for the formation of hook zones  14 . The resulting fastener product  60 ′ (FIG. 7) has “self-fastening” capability, i.e., hook zones  14  are capable of engaging the exposed loops of laminated loop barrier material  70 ′.  
         [0032]    Referring still to FIG. 3 and now also to FIGS. 8 and 8A, another method for producing a fastener product having discrete fastener element bearing regions utilizes a cylindrical sleeve  80  having apertures  82  located about its periphery. Sleeve  80  is positioned over the peripheral molding surface of mold roll  36  during the molding process so that the sleeve serves as a barrier to prevent molten resin (e.g., resin  32  in FIG. 3) from entering mold cavities that do not correspond with openings  82 , while allowing resin to enter cavities  40 ′ that do correspond with openings  82 . The result is a product such as fastener product  10  (FIGS. 1 and 1A) with a base  12  made up of thermoplastic resin and a number of discrete zones  14  of molded fastener elements  16  (or fastener element stems, as described above) extending integrally from the base. Advantageously, by using sleeve  80 , no barrier material is expended, i.e., the barrier material does not become permanently bonded to the fastener product as it is produced.  
         [0033]    In yet another embodiment, illustrated in FIG. 9, an endless belt  90  is used in a manner similar to the sleeve described above with reference to FIGS. 8 and 8A (and FIG. 3). The belt, while also not being expended, allows for a more extensive series or pattern of apertures  92  than does the sleeve, due to its greater overall diameter, i.e., the peripheral surface area of the belt can be manifold greater than that of the sleeve simply by increasing the belt length, thus allowing for more apertures and more complex aperture patterns than the sleeve. As illustrated in FIG. 9, belt  90  is positioned to pass through nip  34  in a manner similar to barrier material  56  (FIG. 3), but, as the fastener product is stripped from mold roll  36 , belt  90  is likewise continuously stripped, by belt roller  98 , from the product itself. Optionally, and depending on the material chosen for belt  90 , the surface of the belt can be continuously treated by application of a release agent  96  at, for example, spray, drip, or wipe station  94 . Again, product  10  of FIGS. 1 and 1A is illustrative of a typical product produced through use of belt  90 , it being noted that more varied and complex patterns of apertures are possible than with sleeve  80 .  
         [0034]    Referring again to FIG. 3, and now as well to FIGS. 10, 10A,  11 ,  11 A,  11 B and  12 , yet another method for producing a product with discrete zones or regions of fastener elements (or stems) on a strip form base is achieved by introducing a backing substrate  100 , such as a film, craft paper or other suitable material with a selectively applied lamination barrier  102  (see FIGS. 10 and 10A) into nip  34 . Unlike the methods described above, this method does not require the use of a barrier material that blocks molten resin from entering selected mold cavities  40  of mold roll  36 , but rather employs a lamination barrier to prevent lamination of the fastener element forming resin  32  to selected, treated regions of backing substrate  100 . As illustrated by dashed lines in FIG. 3, in one example of the present method, lamination barrier  102  is printed onto desired areas of backing substrate  100  at a print station  104 . Print station  104  can comprise rollers, a masked or unmasked sprayer, a controlled wiping or dripping device, or any other apparatus for applying lamination barrier  102  to backing substrate  100 , in a patterned or unpatterned manner. The resulting composite  106  (i.e., substrate  100  with lamination barrier  102  as shown in FIGS. 10, 10A), having lamination barrier printed regions  114  and unprinted regions  116 , is then introduced into nip  34  between molten resin  32  and pressure roll  38 . Pressure in nip  34  forces resin  32  into all of the exposed mold cavities  40  of mold roll  36  to form fastener elements (or stems), while excess resin in the nip forms a resin layer that is pressed against composite  106 .  
         [0035]    The intermediate product  118  (FIGS. 11, 11A) that exits nip  34  includes underlying composite  106  (i.e., a strip-form base of the product) and a resin layer  108  with integrally molded fastener elements  16  (or stems, as described above) formed as protrusions from surface  110  of resin layer  108 . Fastener elements  16  (or stems) are present across substantially one entire surface  110  of resin layer  108 . Meanwhile, the surface  112  of resin layer  108  opposite the fastener elements  16  is permanently bonded to the unprinted regions  116 , i.e., those areas that have not been coated with overprint material  102 , of film  100 , but resin layer  108  does not effectively bond to printed regions  114  of backing substrate  100 . As illustrated more clearly in FIG. 11B, the bonding between resin layer  108  and backing substrate  100  in unprinted regions  116  occurs by the partial encapsulation of the resin with the backing, or the intermingling of mers of the resin layer and the backing substrate if both materials are polymeric, in encapsulation zone  200 .  
         [0036]    Referring also to FIG. 12, the portions of backing substrate  100  that have not been permanently bonded to resin layer  108  may then be removed at a station  120  (FIG. 3) by a number of methods such as registering the bonded pattern of intermediate product  118  to a correspondingly shaped die cutter and “kiss” cutting, i.e., cutting only through the thermoplastic base substrate of the product along the perimeter of the unbonded regions  114  (cut along lines labeled C in FIGS. 11, 11A) while leaving the backing substrate intact, and stripping away the unbonded thermoplastic base and its integrally attached fastener elements, i.e., removing the “ladder” portion. The result is a fastener product  130  including backing substrate  100  with longitudinally discrete regions  170  of fastener elements  16  each region being permanently bonded by a layer  108  of thermoplastic resin from which the fastener elements  16  (or stems) are integrally molded to extend. The removed ladder portion can then be recycled or, alternatively, used as a fastener product or as a component for another fastener product.  
         [0037]    The lamination barrier technique described immediately above can be used to produce a tab product such as that illustrated in FIG. 13. Tab  140  has area  142  of backing substrate  144  permanently bonded to a fastener element-bearing, thermoplastic layer portion  146  while an unbonded area  148  of backing substrate  144  remains free from extension  150  of thermoplastic layer portion  146 . Tab  140  can be attached to another substrate  160 , e.g., a margin of a diaper laminate, by inserting a portion of substrate  160  between unbonded area  148  of backing substrate  144  and extension  150  of thermoplastic layer portion  146 . Alternatively, as illustrated in FIG. 14, substrate  160  can be attached to tab  140  by positioning a portion of substrate  160  beneath bonded area  142  of backing substrate  144  and then folding unbonded area  148  of backing substrate  144  back beneath the portion of substrate  160 . In either of the applications illustrated in FIGS. 13 and 14, the substrate portion can be attached to tab  140  by known methods, e.g., adhesive or otherwise, to provide a fastening tab on substrate  160 .  
         [0038]    The lamination barrier technique described immediately above can employ various types of lamination barriers to prevent bonding of resin  32  with backing substrate  100 . For example, various printing inks including varnish overprint are suitable. Such overprint coatings have melt-points that are substantially higher than most typical thermoplastic films, which can serve as a backing substrate  100 . For example, printed packaging film will not thermally seal together if printing ink exists between seal layers. The ink needs only to exist on one film surface to prevent a seal from occurring. This anti-sealing aspect of printing ink or varnish overprint prevents lamination to occur during the fastener element forming process described above. This allows for the formation of discrete hook zones. Such hook zones can be produced by printing overprint on a backing substrate (such as polyethylene packaging films) everywhere hooks are not wanted. Once run through the fastener element forming process (FIG. 3), fastener elements are only laminated to areas of the backing substrate that are not coated with the overprint. These areas can then be registered to a die profile, “kiss cut” free from the backing substrate and the non-laminated, i.e., unbonded, thermoplastic web stripped from the laminated, i.e., bonded, one. Thus yielding a backing substrate with permanently bonded hook zones on it. Any shape which can be printed and die cut can be thus manufactured.  
         [0039]    An example of an appropriate overprint coating is an overprint varnish such as that provided by ARCAR GRAPHICS as part # AWX5-92105-401. An example of an appropriate backing substrate to which the overprint coating is selectively applied is an adhesive laminated packaging film such as a composite with one side being a 48 Ga. PET and the other side being a 2 mil (0.05 mm) thick polythylene with 2-3% EVA, the polyethylene face surface treated to 40 dyne (40×10 −5 N). Another example of an appropriate backing substrate to which the overprint coating can be applied is a paper known in the industry as 20# natural kraft.  
         [0040]    For example, in using the packaging film composite as the backing substrate in the lamination barrier method described above with reference to FIG. 3, the packaging film is coated in discrete areas, e.g., with a coating thickness of as little as 0.001 inch (0.03 mm), with the above described overprint varnish, and subsequently the film is run with its uncoated PET face against the back-up roll, i.e., pressure roll  38  (FIG. 3). The film&#39;s partially coated polyethylene face is thereby positioned such as to wrap against the fastener element molding roll  36 , but for the polyethylene resin  32  that is provided from the extruder head  30 . This results in adding a layer of the extruded resin  32  to the packaging film&#39;s PE face just before the combined materials entry into the nip. Fastener elements (or stems) are then molded, e.g., in a uniform pattern across the width of the nip, by mold roll  36  from the extruded resin layer, the fastener elements (or stems) being securely anchored to the base packaging film in only those areas that were not treated with overprint varnish. The extrusion layer becomes virtually inseparable from the base packaging film&#39;s layer in these untreated areas. However, where the packaging film has been treated with the overprint varnish, the extrusion layer remains unbonded to the film. The overprint coated/uncoated transition line produces a sharp, well-defined bond/no-bond edge.  
         [0041]    The backing substrate can be a web of virtually any material such as paper, plastic resin or cloth that can be printed with overprint. This means that the backing substrate can be of one material while the hooks can be of another. This allows each component to be selected based on downstream processing or functional need requirements. For example: a multilayer substrate could be selected for toughness, electrical conductivity and thermal sealibility (Nylon/AL/PE). Hook resin can be different from the backing substrate material. (PP hooks on a PE film allow PP hooks to be thermally bonded to PE film.)  
         [0042]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the technique for forming the fastener elements of the above described fastener products can be a multi-step process wherein the molding operation involves the formation of stems only which are subsequently shaped to form engaging heads. Such techniques are known in the art, and the above methods can be used to form discrete regions of such stems on a substrate, the stems being later shaped to form engaging heads to thereby produce a fastener product with discrete regions of fastener elements. Accordingly, other embodiments are within the scope of the following claims.