Abstract:
A fastener product includes a planar base, multiple discrete plateaus molded integrally with and extending from an upper surface of the base each plateau having an upper surface that is smaller in area than an overall area of the base covered by the plateau, and an array of discrete fastener elements integrally molded with and extending from the upper surface of the plateau. The product is molded on a mold roll covered by a sleeve either made of a resilient material or having apertures intersecting an inner surface of the sleeve at an inner opening that is smaller than an outer opening of the aperture at an outer sleeve surface to form an edge of the fastener product of decreased sharpness.

Description:
TECHNICAL FIELD 
     This invention relates to discrete fastener regions, and more particularly to fastener elements, capable of engaging a material, extending from discrete regions of a base or substrate. 
     BACKGROUND 
     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. 
     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 were subsequently changed, the specialty tool would require redesign and or rebuilding to accommodate the change. 
     SUMMARY 
     In an aspect, a method of making a fastener product having discrete regions of fastener element stems extending from a section of a strip-form base is provided. The method includes: providing a gap formed along a peripheral surface of a rotating mold roll; the mold roll having a plurality of cavities extending from the peripheral surface; positioning a compliant sleeve about the mold roll, the sleeve covering select ones of the 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 and the aperture, while the resin remains blocked from said selective ones of the cavities by the sleeve, to form fastener element stems as projections extending from the section, the section extending from the strip form base, the sleeve compressing under pressure in the gap; solidifying the resin; and stripping the solidified resin from the peripheral surface of the mold roll by pulling the projections from their cavities. 
     In another aspect, a method of making a fastener product having discrete regions of fastener element stems extending from a base includes: providing a gap formed along a peripheral surface of a rotating mold roll, the mold roll having an array of cavities extending from the peripheral surface; positioning a sleeve about the mold roll, the sleeve having an outer surface and an inner surface and defining at least one aperture extending between the inner and outer surfaces to expose a region of the array of cavities, the aperture intersecting the inner surface of the sleeve at an inner opening that is smaller than an outer opening of the aperture at the outer sleeve surface; introducing the sleeve to the gap; 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 the region of the array of cavities and the aperture to form fastener element stems as projections extending from an upper surface of a plateau, the plateau molded integrally with and extending from the base and the upper surface of the plateau is smaller in area than an overall area of the base covered by the plateau; solidifying the resin; and stripping the solidified resin from the peripheral surface of the mold roll by pulling the projections from their cavities. 
     Some embodiments include a compliant sleeve. In some cases the sleeve resiliently compresses, (i.e, the sleeve has an elastic property allowing portions of the sleeve, following compression, to at least substantially assume its original, uncompressed configuration once outside a pressure region, for example, once outside the gap region). In some embodiments, the compliant sleeve is resiliently expanded about the mold roll. This expansion allows for positioning of the mold roll sleeve about the mold roll. 
     Some embodiments include a mold roll sleeve having an aperture that includes a chamfered or a radiused edge. Chamfered or radiused edges of the aperture form a fastener product having a corresponding chamfered or radiused edge. 
     In some versions, the cavities of the mold roll comprise a number of shapes allowing for the formation of a variety of projections. For example, the cavities can be stem-shaped thus forming projections extending from the section to a distal tip of the projection. The distal tips of the projections can then be post-formed, including deforming the distal tips to form loop-engaging heads on the projections. In some embodiments, the cavities include a loop-engaging head shape thus forming projections with loop-engaging heads. The loop-engaging head shapes can be hooks, for example. 
     Some embodiments also include introducing a backing material to the molten resin while the resin is disposed in the gap. The backing material can be a nonwoven, printable cloth, plastic film, a resiliently extensible material, paper, woven fabric or the like, as examples. 
     In another aspect, a fastener product includes a planar base, multiple discrete plateaus molded integrally with and extending from an upper surface of the base each plateau having an upper surface that is smaller in area than an overall area of the base covered by the plateau, and an array of discrete fastener elements integrally molded with and extending from the upper surface of the plateau. 
     In another aspect, a fastener product includes a base comprising a first material, a plateau molded integrally with and extending from the base and having an upper surface that is smaller in area than an overall area of the base covered by the plateau, the plateau having at least one layer comprising a second material, and an array of fastener elements integrally molded with and extending from the upper surface of the plateau. 
     Various embodiments include fastener elements of different shapes including hook-shapes and/or mushroom-shapes, for example. In some embodiments, the plateaus include a radiused and/or a chamfered edge allowing for a relatively smooth transition from a surface of the base to an upper surface of the plateau. An advantage of this smooth transition, among others, is that the radiused or chamfered edge provides a softer “feel” for a user coming in contact with a surface of the fastener product. 
    
    
     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 
     FIG. 1 illustrates a method and apparatus used to form a fastener product. 
     FIG. 2 illustrates a method and apparatus for forming a fastener product. 
     FIG. 3 illustrates a mold roll sleeve positioned about a mold roll. 
     FIG. 4 illustrates a side view of a mold roll sleeve positioned about a mold roll. 
     FIG. 4A is a detail illustration of a portion of the mold roll and mold roll sleeve. 
     FIG. 5 illustrates a compressed mold roll sleeve positioned about a mold roll. 
     FIG. 5A is a detail view of an uncompressed mold roll sleeve. 
     FIG. 5B is a detail view of a compressed mold roll sleeve. 
     FIG. 6 is a fastener product formed by a noncompliant mold roll sleeve. 
     FIG. 7 is a fastener product formed by a compliant mold roll sleeve. 
     FIG. 8 is a mold roll sleeve with a chamfered edge. 
     FIG. 9 is a molded product having a plateau integral with a chamfered edge. 
     FIG. 10 illustrates a method and apparatus used to form a multi-layer fastener product. 
     FIG. 11 illustrates a method and apparatus used to form a multi-layer fastener product. 
     FIGS. 12-12D illustrate a multi-layer fastener product. 
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     Referring to FIGS. 1 and 2, methods of producing fastener products are shown. 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 FIGS. 1 and 2 are schematic and are not to scale. Referring particularly to FIG. 1, an extrusion head  10  supplies a continuous sheet of molten resin  12  to a nip or gap  14  between a molding roll  16  and a counter rotating pressure roll  18 . Mold roll  16  contains an array of miniature, mold cavities  20  extending inward from its periphery for molding at least a portion of the fastener elements. The array of cavities  20  extends substantially about the entire periphery of mold roll  16 . Pressure in the nip  14  forces resin  12  to enter and at least partially fill the exposed mold cavities  20 , 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  22 . 
     Referring still to FIG. 1, in some embodiments, cavities  20  of mold roll  16  have a stem forming portion and an engaging head forming portion 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 with hooks that overhang a base. In these embodiments, the solidified product stripped from mold roll  16  has fastener elements capable of engagement. Referring now to FIG. 2, in other embodiments, cavities  20  of mold roll  16  have only a stem forming portion. In these embodiments, the product stripped from mold roll  16  has stems, extending from the base that can be post-treated to form engaging heads. For example, after molding and stripping the product from mold roll  16 , the tops of the molded stems can be deformed by pressure with a pressure roller  28  and/or heated with a heater  30  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. Additionally, a backing material, such as a preformed film, a loop material, a printable cloth, a resiliently extensible material, paper, a woven or the like, may be introduced into the nip to form a fastener product having a backing substrate. 
     Referring now to FIGS. 1 and 2, mold roll  16  has a mold roll sleeve  32  positioned about the periphery of mold roll  16 . Sleeve  32  is positioned over the peripheral molding surface of mold roll  16  during the molding process so that the sleeve serves as a barrier to prevent molten resin  12  from entering mold cavities that do not correspond with openings while allowing resin to enter cavities that do correspond with openings. 
     FIGS. 3-4A illustrate a sleeve  32  positioned about the peripheral molding surface of a mold roll  16 . Referring now to FIG. 3, sleeve  32  contains apertures  34  exposing select areas of the peripheral molding surface of the mold roll  16 . Although select areas of the mold roll surface are exposed, other areas are blocked thus preventing the flow of resin into select cavities  20 . 
     Referring to FIG. 4, a side view illustration of a mold roll  16  having a sleeve  32  positioned about its molding surface is shown. Apertures  34  extend from an outer surface of sleeve  32  to an inner surface of sleeve  32  to expose hook-shaped cavities  20 . See also FIG.  4 A. Mold roll sleeve  32  is comprised of a compliant material, (i.e., a material that has a hardness of, for example, less than 90 Shore D) that allows the sleeve  32  to compress as the sleeve  32  and resin enter the nip or gap of the mold roll  16  and the pressure roll  18 . See FIG.  5 . This compression of the sleeve  32  decreases the outer diameter of the sleeve  32  and mold roll  16  assembly, at least in the nip region. 
     Referring now to FIG. 5A, a detailed view of mold roll sleeve  32  is shown in an uncompressed state. The distance from the outer surface  35  of the sleeve  32  to the inner surface  36  of the sleeve  32  is “t 1 .” Referring now to FIG. 5B, a detailed illustration of the sleeve  32  is shown in a compressed state. As shown, the profile of the sleeve  32  is reduced. This reduction in profile is caused, for example, by the pressure exerted against the outer surface  35  of the sleeve  32  by the resin and the pressure roll. The distance from the outer surface  35  of the sleeve  32  to the inner surface  36  of the sleeve is given by “t 2 .” Due to the compression, the distance t 1  is greater than t 2 . 
     Referring to FIGS. 6 and 7, fastener products  40  and  50  are illustrated. Referring particularly to FIG. 6, fastener product  40  was formed using a sleeve having a wall thickness t 1 , formed of non-compliant material (i.e., the material has a relatively high hardness, for example, greater than 90 Shore D). Fastener product  40  comprises a sheet-form base of resin  42  having fastener elements  44  extending outwardly from plateau  43 , which is integrally molded with base  42 . Fastener product further includes a backing material  46 , e.g., a non-woven, woven, film, loop material, paper, etc., bonded to a surface of the resin base  42 . As noted, base  42  includes plateau  43 . Plateau  43  is formed by the “cavity” provided by the aperture  34 . The distance, d 1 , corresponds to the distance between an outer surface of the base  42  to an upper surface of the plateau  43  and is approximately equal to t 1 . See FIG.  5 A. 
     By contrast, referring now to FIG. 7, fastener product  50 , formed using a compliant mold roll sleeve  32  having an uncompressed wall thickness (t 1 ) and a compressed wall thickness (t 2 ), is shown. Fastener product  50  also comprises a sheet-form base of resin  42  having fastener elements  44  extending from plateau  48 , which is integrally molded with base  42 . Fastener product  50  also includes a backing material  46 , e.g., a non-woven, woven, film, loop material, paper, etc., bonded to a surface of the resin base  42 . As noted, fastener product  50  includes a plateau  48  extending from the surface of the base  42  formed by the “cavity” provided by the aperture  34 . As can be seen, the distance d 2  is less than the distance d 1  of the product  40  of FIG.  6 . This is accomplished by employing the compliant sleeve  32  having a compressed wall thickness, t 2 , that is less than the uncompressed thickness, t 1 . Because t 2  is approximately equal to d 2 , d 2  is less than d 1 . See also FIG.  6 . 
     FIG. 8 shows a mold roll sleeve  52  having chamfered edges  54  and  55 . While chamfered edges  54  and  55  extend from an outer surface  56  of the sleeve  52  to an inner surface  58  of the sleeve  52 , the edges  54  and  55  may also be only partially chamfered. While edges  54  and  55  are chamfered, the edges could include a radius or other like configuration. 
     Chamfered edges may be formed by a variety of techniques including laser cutting, machining, etching, including photochemical etching and/or the like. Edges  54  and  55  are chamfered at 45 degrees, but the edges may be chamfered at an angle less than 90 degrees. 
     Referring now to FIG. 9, a fastener product  60  made in accordance with one or more of the above embodiments is illustrated. Fastener product  60  includes a base  62  and a plateau  64  integral with the base  62  having fastener elements  66  extending from plateau  64 . Fastener elements  66  comprise hooks, but may also be formed as, for example, mushrooms, flat tops, and/or stems. Plateau  64  also includes edge(s)  66  that are chamfered, providing a relatively smooth transition from the sheet-form base  62  to a surface  68  of plateau  64 . While edge(s)  66  are chamfered at an angle less than 90 degrees, e.g., a 45 degree chamfer, the edges could include a radius or other like configuration. 
     Referring now to FIGS. 10 and 11, suitable processes for forming a two-polymer fastener are shown. Referring particularly to FIG. 10, a first extruder  72  extrudes a first, hook-forming polymer  74  onto mold roll sleeve  76 . Mold roll sleeve  76  can be formed of either a compliant or a non-compliant material, as noted above. The mold roll sleeve  76  includes apertures  77  having radiused edge  79 . It should be noted that while edge  79  is shaped to form a product with a convex edge, edge  79  can be shaped to form a product with a concave edge. The extruder  72  forces some of the polymer into hook-forming cavities  78  and leaves a layer of polymer on the surface of the mold roll sleeve  76 . As mold roll  80  rotates in the direction of arrow A, doctoring blade  82  removes some or the entire polymer on the surface of the mold roll without disturbing the polymer in cavities  78 . The removed polymer, which has been exposed to air while on the mold roll sleeve  76  and may have begun to solidify, may be either discarded or returned to a hopper for remelting. The thickness of polymer left on the surface of the roll sleeve by the doctoring blade will depend, in part, on how close the blade is positioned to the surface of the mold roll (the position is adjustable in the direction indicated by arrow B). In some cases, the sharp, distal end of blade  82  rides against the mold roll sleeve, thereby literally scraping off essentially the entire polymer on the surface of the sleeve. In such cases it is recommended that the end of the blade be coated with a lubricious material to avoid damaging the surface of the mold roll sleeve. In other cases, the position of the blade is adjusted to leave a predetermined thickness of polymer on the sleeve, to become a part of the base of the product. In such cases, the doctoring blade effectively trims the polymer thickness rather than actually “scraping” against the surface of the mold roll sleeve. Next, a second extruder  81  extrudes a second, base-forming polymer  85  onto the surface of the mold roll sleeve (or onto any of polymer  74  left on the surface of the roll by blade  82 ). A gear pump  83 ,  84 , is positioned at the outlet of each extruder, to accurately control the rate of polymer delivered to the mold roll sleeve. The finished fastener product  86  is stripped from the mold roll  80  by passing it around exit roll  88 . 
     A backing material (not shown) may also be introduced to the resin forming a fastener product having a backing material formed of, for example, loop material, preformed film, nonwoven, printable cloth, a resiliently extensible substrate, woven fabric, paper or the like. 
     Referring now to FIG. 11, the hook-forming polymer is applied to the mold roll sleeve by an extruder  90 , and most of the polymer is scraped form the surface of the mold roll sleeve by a doctoring blade  92 , leaving a thin film of polymer, as described above with reference to FIG.  10 . The base-forming polymer  94  is then laminated to the thin film of hook-forming, polymer while the latter is still on the mold roll, such as in the nip between the mold roll and roll  96 , as shown. 
     Examples of various fasteners that can be formed using the process shown in FIGS.  10  and/or  11  (or modifications of this process) are shown in FIGS. 12-12D. 
     FIG. 12 shows a fastener  100 , in which the plateau  104  includes a chamfered edge  103  of less than 90 degrees, for example, a 45 degree chamfered edge  103 , and the hooks  102  are formed of a first polymer and the base  106  is formed of a second polymer. Using the process shown in FIGS. 10 or  11 , such a fastener can be formed by scraping substantially the entire first polymer off of the surface of the sleeve prior to applying the second polymer. 
     FIG. 12A shows a fastener  110 , in which the hooks  112 , the plateau  114 , having a radiused edge  103 , and the upper portion  116  of the base  18  are formed of a first polymer, and the lower portion  120  of base  118  is formed of a second polymer. Using the process shown in FIGS. 10 or  12 , such a fastener can be formed by adjusting doctoring blade  46  away from the sleeve surface so that a thin layer of the first polymer remains on the mold roll surface when the second polymer is applied. When using a stiff first polymer and a flexible or stretchable second polymer, the layer of first polymer is preferably sufficiently thin, as determined by the positioning of the doctoring blade, to enable the rupture of the thin layer of first polymer upon the initial stretch of the second polymer layer, such as during the initial engagement of a diaper tab. Subsequently, the rigidity of the thin layer of the first polymer does not detract from the stretchability of the base of the fastener product. 
     FIG. 12B shows a fastener  120  having a plateau  123  with a radiused edge  103 , in which the hooks  122  and an upper portion of the plateau  123  are formed of a first polymer  124  and the lower portion of the plateau  123  is formed of a second polymer  126 , and the base  128  is formed of a third polymer  130 . To form this fastener, the processes shown in FIGS. 10 or  11  are modified so that the first extruder applies an amount of the first polymer that only partially fills the mold cavities and the aperture, and then another extruder (not shown in FIGS. 10 or  11 ) applies the second hook-forming polymer to completely fill the aperture. The process then continues as shown in FIGS. 10 or  11 , with scraping and application of the base-forming polymer by extruder. If the two polymers  124 ,  126  are not compatible, or do not adhere well to each other, a thin tie layer of adhesive, or a third polymer that adheres well to both polymers  124  and  126 , can be applied between polymers  124  and  126 . This can be accomplished by replacing an extruder with a co-extrusion die, or by other known methods of applying tie layers. 
     FIG. 12C shows a fastener  140 , having a radiused edge  103 , in which the hooks  142  are formed of three different polymers  144 ,  146 ,  148 . This fastener would be formed in a manner similar to that described below with reference to FIG. 12D, adding a further extruder to apply the third plateau-forming polymer. This embodiment can provide combinations of properties difficult to obtain with only two polymers. Alternatively, the middle polymer  146  may be used as a “tie layer” to bond polymers  144  and  148  if, for example, these polymers are incompatible or do not adhere well to each other. 
     FIG. 12D shows a fastener  150 , having a radiused edge  103 , in which an upper layer  153  of the base  152  and a lower portion  154  of plateau  156  are formed of a first polymer, and the upper portion  158  of the plateau  156  is formed of a second polymer. This fastener would be formed by the process of FIGS. 10 or  11 , by only partially filling the aperure of the sleeve using an extruder, and then completing the filling of the aperture with an additional extruder. 
     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 fastener product may further include a backing material comprising, for example, loops, non-woven material, a printable cloth, or the like. Accordingly, other embodiments are within the scope of the following claims.