Abstract:
Stretchable fastener products are formed by providing a sheet-form fastener tape, slitting the fastener tape to form longitudinally extending bands of fastener tape and separating the longitudinally extending bands to space the fastener tape bands transversely apart. The spaced bands are attached to a sheet form elastic web to form a stretchable fastener product. In some examples, the stretchable fastener product is formed continuously in conjunction with manufacture of the sheet-form fastener tape.

Description:
CLAIM OF PRIORITY  
       [0001]    This application claims priority under 35 USC § 120 to PCT/US01/07939, filed Mar. 12, 2001, which claims priority from U.S. patent application Ser. No. 60/189,136, filed on Mar. 14, 2000, the entire contents of both of which are hereby incorporated by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to stretchable fasteners and especially to stretchable fasteners that may be practical and cost efficient for fastening applications where elasticity and flexibility is desired.  
         BACKGROUND  
         [0003]    Stretchable fasteners that carry hook and loop closures are desirable as part of infant and adult diapers, surgical gowns, and other garments and wraps. The fasteners typically comprise sheet, film or non-woven webs of elastic construction that have embossing or other surface patterns for grasping by the user. To the back of such an elastic web, a tape of fastener elements is secured, forming a laminate structure. The fastener tape is typically made of a synthetic resin that is not stretchable, and the resulting laminate is relatively stiff, does not stretch, and does not present the desired degree of cloth-like feel.  
           [0004]    It is desirable that the substance of the tab and the associated fastener tape provide an integral, stretchy component that achieves the desired qualities, such as elasticity, flexibility and cloth-like feel.  
         SUMMARY  
         [0005]    The invention features, in several of its aspects, a method of forming stretchable fasteners. The fasteners have a base of synthetic resin, and an array of loop-engageable fastener elements integrally molded with and extending from the base.  
           [0006]    According to one aspect of the invention, a method of forming a stretchable fastener product includes providing a sheet-form fastener tape, processing the fastener tape including slitting to form longitudinally extending bands of fastener tape and to space said fastener bands transversely apart, and attaching the transversely spaced apart fastener bands to a sheet form elastic web.  
           [0007]    In some cases, the elastic web extends across the fastener bands as well as across spaces between adjacent spaced apart bands and in other cases the elastic web extends only across spaces between adjacent spaced apart bands.  
           [0008]    Transversely spaced apart bands are formed by passing the slit fastener tape bands through a separator that separates the bands and spaces them transversely apart, or by removing every other adjacent band of the slit fastener tape bands. The transversely spaced apart fastener bands are attached to the elastic web by thermal fusion, ultrasonic welding, or an adhesive. In one embodiment, the every other adjacent band that has been removed is attached to a second sheet form elastic web to form a second stretchable fastener.  
           [0009]    Certain, exemplary embodiments of the invention have one or more of the following features. The fastener tape comprises a base of synthetic resin, and an array of loop-engageable fastener elements integrally molded with and extending from a first surface of the base. The array of loop-engageable fastener elements has a density of the order of 500 or more fastener elements per square inch. The array of loop-engageable fastener elements has a density of the order of 1000 or more fastener elements per square inch. The fastener elements have relatively stiff stems and hook-shaped heads and in some instances the stems have a greater cross-section than the hook-shaped heads. The fastener elements have relatively stiff stems and disc-shaped heads. The disc-shaped heads have a flat top surface.  
           [0010]    In some embodiments, the transversely spaced apart fastener bands are attached to the elastic web by supporting the spaced apart fastener bands on a support roll, wherein the loop-engageable fastener elements are in contact with a surface of the support roll, while simultaneously pressing and heating the elastic web against a second surface of the base of the fastener tape bands. A heated laminating roll or a continuous belt is arranged to press the elastic web against the second surface of the base of the fastener bands to promote lamination.  
           [0011]    The support roll may have circumferential recesses, which are configured to support the fastener bands and to position the second surface of the base of the fastener bands at the surface of the support roll.  
           [0012]    In some cases, a backing is attached to the second surface of the base of the fastener bands. The backing may be a heat-sensitive adhesive, and the method then includes the step of activating the adhesive before engagement with the elastic web.  
           [0013]    According to another aspect of the invention, a stretchable fastener product is formed by first introducing a moldable first material to a continuously rotating mold roll to form a sheet-form fastener having a base conforming to a surface of the mold roll and multiple rows of molded fastener elements integral with the base. The rows extend in a longitudinal direction of the sheet-form fastener and the fastener elements are formed by mold cavities of the mold roll. The thus-formed sheet-form fastener is then slit into longitudinally extending band portions carrying multiple rows of the fastener elements. Spaces are then created between adjacent bands transverse to the longitudinal direction, and subsequently a web of a second material different from the material of the fastener elements is joined to the transversely spaced apart bands.  
           [0014]    Exemplary embodiments may have one or more of the following features. The second material is resiliently extensible. The slit bands of the fastener product are removed from the mold roll, and are passed through a separating device that develops space between the adjacent bands transversely to the longitudinal direction. Thereafter the bands are introduced onto a surface of a support roll, and the web of the second material is joined to the bands by pressure and heat while the fastener bands are on the support roll. The support roll may have circumferential recesses, which are configured to support the fastener bands and to position the second surface of the base of the fastener bands at the surface of the support roll.  
           [0015]    In some embodiments the fastener elements are loop-engageable hooks molded of synthetic resin of density of the order of 1000 or more fastener elements per square inch. The fastener elements may have relatively stiff stems of greater cross-section than their loop-engageable hooks. The hooks of the fastener elements of a given band may engage the bottom of the respective recess and may be collectively self supporting under the pressure of laminating, serving to assist in producing laminating pressure by which the bands are joined to the second material. A heated laminating roll or a continuous belt is arranged to press the second material against the second surface of the fastener bands to promote lamination.  
           [0016]    In some embodiments a sheet-form fastener is formed on the mold roll having bands of fastener elements spaced apart from bands of material to be removed. The sheet-form fastener is the slit and the bands of material to be removed are removed while the bands of fastener elements remain on the mold roll. While the fastener elements thus continue to reside in their respective mold cavities, and with the mold roll serving as a pressure roll, a second material is joined to the bands. The second material is a molten resin introduced to the mold roll into contact with regions vacated by the bands of material that have been removed. Portions of the mold roll corresponding to the spaces between the bands of fastener elements may be substantially smooth cylindrical sections. In some cases the second material is introduced across the width of the bands of fastener elements as well as the vacated spaces between the bands of fastener elements.  
           [0017]    In some embodiments, a second parallel roll forms a nip with the mold roll, and an extruder is arranged to deliver molten resin to the nip to serve as the second material, the nip being effective to apply the resin as a layer that bridges between the bands of fastener material.  
           [0018]    The fastener elements are loop engageable hooks molded of resin selected from the group consisting of polyester, polyethylene, polypropylene, polyamide and copolymers and alloys thereof. The second material is comprised of a resilient resin having an elongation in the range of 50% to 300% and a recovery of at least 75%. The second material is selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, elastomeric copolymers containing polyethylene terephthalate (PET), thermoplastic olefins, and natural or synthetic rubber. The second material may also be a preformed nonwoven loop material, the loop material being releasably engageable by the fastener tape. The nonwoven material may be a needled web having a basis weight of less than about 4 oz/square yard.  
           [0019]    In some embodiments, each of the fastener bands and spaces between the fastener bands has a width of ¼ inch (6.4 mm) or less. In other embodiments each of the fastener bands and spaces between the fastener bands has a width greater than ¼ inch (6.4 mm). In other embodiments, each of the fastener bands has a width less than or equal to ¼ (6/4 mm) inch, and each of the spaces between the fastener bands has a width greater than or equal to ¼ inch (6.4 mm). In yet other embodiments, each of the fastener bands has a width greater than or equal to ¼ (6/4 mm) inch, and each of the spaces between the fastener bands has a width less than or equal to ¼ inch (6.4 mm).  
           [0020]    According to another aspect of the invention, a method of forming a stretchable fastener product is disclosed, the method including introducing a moldable first material to a continuously rotating mold roll to form a sheet-form product having a base conforming to a surface of the mold roll and multiple rows of stem elements integral with the base, the rows extending in a longitudinal direction of the sheet-form fastener, the stems formed by mold cavities of the mold roll. The method also includes heating a tip portion of the stems, contacting a cooled roller to the tip portion of the stems to produce disc-shaped engaging heads on the stems, slitting the thus-formed sheet-form fastener into longitudinally extending band portions carrying multiple rows of the fastener elements, creating space between adjacent bands transverse to the longitudinal direction, and subsequently joining to the transversely spaced apart bands a web of a second material different from the material of the fastener elements.  
           [0021]    An exemplary embodiment of this aspect of the invention may include creating space between adjacent bands by directing selected bands to a first station and directing bands adjacent the selected bands to a second station, whereby the selected bands form a first set of transversely spaced apart bands and the bands adjacent the selected bands form a second set of transversely spaced apart bands, each of the first and second stations being provided for performing the joining operation, whereby the first set is laminated to a first web of the second material to form a first stretchable fastener product and the second set is joined to a second web of the second material to form a second stretchable fastener product. Other variations of this aspect of the invention can include any of the features described above with reference to other aspects of the invention.  
           [0022]    Another aspect of the invention is a method of simultaneously forming multiple stretchable fastener products including providing a sheet-form fastener tape, slitting the sheet-form fastener tape to form longitudinally extending bands of fastener tape, directing a first set of the bands to a first attachment station and directing a second set of the bands to a second attachment station, the bands of the first and second sets being selected so that each set comprises transversely spaced apart fastener bands, and attaching the first set of transversely spaced apart fastener bands to a sheet form elastic web at the first attachment station and attaching the second set of transversely spaced apart fastener bands to a sheet form elastic web at the second station to simultaneously form multiple stretchable fastener products.  
           [0023]    Variations of this aspect of the invention can include any of the features described above with reference to other aspects of the invention.  
           [0024]    According to another aspect of the invention, a stretchable fastener product is provided by employing one of the above-described methods. The stretchable fastener has an elastic web, and multiple fastener tape bands attached to the elastic web and configured to be oriented parallel to each other and spaced apart from each other.  
           [0025]    Variations of this aspect of the invention can include any of the features described above with reference to other aspects of the invention.  
           [0026]    In some embodiments, each fastener band comprises a base of synthetic resin, and an array of loop-engageable fastener elements integrally molded with and extending from a first surface of the base. The array of loop-engageable fastener elements may have a density of the order of 1000 or more fastener elements per square inch. The fastener elements may have relatively stiff stems and hook-shaped heads, and the stems may have greater cross-section than the hook-shaped heads. A backing may be attached to a second surface of the base, and the backing may be a heat-sensitive adhesive. The resin may be selected from the group consisting of polyester, polyethylene, polypropylene, polyamide and copolymers and alloys thereof. The elastic web may be made of a resilient resin and may have an elongation in the range of 50% to 300% and a recovery of at least 75%. The elastic web may be selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, elastomeric copolymers containing PET, thermoplastic olefins, and natural or synthetic rubber.  
           [0027]    The elastic web may be a preformed nonwoven loop material, and the nonwoven material may be a needled web having a basis weight of less than about 4 oz/square yard.  
           [0028]    The fastener bands and spaces between the fastener bands may each be of the order of ¼ inch or less wide and ¼ inch or less wide, respectively.  
           [0029]    According to another aspect of the invention, a stretchable fastener product includes multiple fastener tape bands and multiple elastic web bands, and edge margins of the elastic web bands are attached to edge margins of the fastener bands. The edge margins of the elastic web bands may overlap or abut the edge margins of the fastener bands.  
           [0030]    Among the advantages of the invention may be one or more of the following. The stretchable fasteners of this invention do not “set”, i.e., stretch partially irreversibly, have hooks with strong structural integrity and are cost efficient.  
           [0031]    Other features and advantages of the invention will be apparent from the following description of embodiments, and from the claims.  
           [0032]    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  
       [0033]    [0033]FIG. 1 is a perspective view of a stretchable fastener having spaced apart bands of fastener tape attached onto an elastic substrate.  
         [0034]    [0034]FIG. 1A is an expanded side view of the stretchable fastener of FIG. 1.  
         [0035]    [0035]FIG. 1B is an expanded side view of the stretchable fastener of FIG. 1A taken in plane  1 B- 1 B.  
         [0036]    [0036]FIG. 1C is an expanded top view of the fastener of FIG. 1.  
         [0037]    [0037]FIG. 1D is an expanded side view of another embodiment of a stretchable fastener.  
         [0038]    [0038]FIG. 2 is an expanded side view of another embodiment of a stretchable fastener having spaced apart bands of fastener tape attached onto an elastic substrate.  
         [0039]    [0039]FIG. 2A is an expanded top view of the fastener of FIG. 2.  
         [0040]    [0040]FIG. 3 illustrates a method and an apparatus for forming the stretchable fastener of FIG. 1.  
         [0041]    [0041]FIG. 3A is an expanded perspective view of the channeled roll  230  in FIG. 3.  
         [0042]    [0042]FIG. 3B is a side view of a channeled roll taken in plane  3 B- 3 B of FIG. 3.  
         [0043]    [0043]FIG. 3C is a cross sectional view of a stretchable fastener taken in plane  3 C- 3 C of FIG. 3.  
         [0044]    [0044]FIG. 3D illustrates a variation of the method and apparatus of FIG. 3.  
         [0045]    [0045]FIG. 4 is a perspective view of a separator that spreads apart the incoming slit fastener bands.  
         [0046]    [0046]FIGS. 4A is a cross sectional view of a separator taken in plane  4 A- 4 A of FIG. 4.  
         [0047]    [0047]FIG. 4B is a perspective view of a separator that creates spaces between the adjacent slit fastener bands by removing every other band of the incoming slit bands.  
         [0048]    [0048]FIG. 4C is a cross sectional view of the separator in FIG. 4B taken in plane  4 C- 4 C in FIG. 4.  
         [0049]    [0049]FIG. 5 illustrates another method and another apparatus for forming the stretchable fastener of FIG. 1.  
         [0050]    [0050]FIG. 5A is an expanded view of area  5 A in FIG. 5.  
         [0051]    [0051]FIG. 5B is a cross sectional view of the apparatus in FIG. 5 taken in plane  5 B- 5 B.  
         [0052]    [0052]FIG. 6A is a side view of the fastener tape  70  in FIG. 5.  
         [0053]    [0053]FIG. 6B is a side view of the slit fastener bands  80  in FIG. 5.  
         [0054]    [0054]FIG. 6C is a side view of the stretchable fastener  100  in FIG. 5.  
         [0055]    [0055]FIG. 7 illustrates another method and an apparatus for forming the stretchable fastener of FIG. 1.  
         [0056]    [0056]FIG. 7A is an expanded view of area  7 A in FIG. 7.  
         [0057]    [0057]FIG. 7B is a side view of the fastener tape  70  in FIG. 7.  
         [0058]    [0058]FIG. 7C is a cross sectional view of the apparatus in FIG. 7 taken in plane  7 C- 7 C.  
         [0059]    [0059]FIG. 8 is a cross sectional view of a slotted die having multiple slot openings.  
         [0060]    [0060]FIG. 9 illustrates another method and an apparatus for forming the stretchable fastener of FIG. 9B.  
         [0061]    [0061]FIG. 9A is a side view of the molded fastener bands  80  in FIG. 9.  
         [0062]    [0062]FIG. 9B is a side view of a stretchable fastener having spaced apart fastener bands attached to elastic bands.  
         [0063]    [0063]FIG. 9C is a side view of another embodiment of a stretchable fastener having spaced apart fastener bands attached to elastic bands.  
         [0064]    [0064]FIG. 10 illustrates another method and an apparatus for forming the stretchable fastener of FIGS. 9B and 9C.  
         [0065]    [0065]FIG. 10A is a cross sectional view of the two separated slotted dies  41  and  51  of FIG. 10 taken along plane  10 A- 10 A.  
         [0066]    [0066]FIG. 10B is an expanded view of the nip area  44  in FIG. 10.  
         [0067]    [0067]FIG. 11 is a top view of a stretchy diaper tab.  
         [0068]    [0068]FIG. 11A illustrates a diaper with a stretchy diaper tab.  
         [0069]    [0069]FIG. 12 is a side view of an alternative fastener element that can be used for the stretchable fastener of FIG. 1.  
         [0070]    [0070]FIG. 13 is a diagrammatic illustration of a method and apparatus for making a stretchable fastener similar to that of FIG. 1, but having fastener elements similar to that of FIG. 12.  
         [0071]    Like reference symbols in the various drawings indicate like elements. 
     
    
     DETAILED DESCRIPTION  
       [0072]    Referring to FIGS. 1 and 1A, a stretchable fastener  100  features spaced apart bands of fastener tape  104 , attached to a sheet-form elastic substrate  102 . Each fastener band  104  has a width w 1  of the order of ⅛ inch and is spaced apart from a neighboring fastener band by a distance w 2  of the order of ⅛ inch. Each fastener band has rows  105  of fastener elements  106  integral with a base layer  108  (FIG. 1A). During use of the stretchable fastener a stress is applied along a stretching direction  112 . The applied stress causes an elongation of the elastic layer  102  parallel to the stretching direction, and when the stress is removed the fastener  100  returns to its original dimensions. In this embodiment, the fastener elements are in the form of J-hooks and extend in rows  105  perpendicular to the stretching direction  112 . The J-hooks have a stiff stem  114  and a hook shaped head  116  (FIG. 1B) pointing in the direction of the arrows (FIG. 1C) and perpendicular to the stretching direction  112 . Adjacent rows of hooks  105  have oppositely oriented hooks  106 , as shown in FIG. 1C. The cross-sectional diameter of the stem d 1  is greater than the cross-sectional diameter of the hook shaped head d 2 .  
         [0073]    In one example, the hooks are of CFM-29 designation, available from Velcro USA Inc. of Manchester, N.H., U.S.A. The CFM-29 hook strip has hooks of only 0.015 inch (0.38 mm) height h, a base thickness t 1  of 0.003 inch (0.08 mm) and a fastener element density of the order of 1000 or more fastener elements per square inch. The thickness t 2  of the elastic substrate is 0.005 inch (0.13 mm) (FIG. 1B).  
         [0074]    The elastic layer  102  is composed of a thermoplastic elastomer, such as Santoprene         , having an elongation in the range of 50% to 300% and a recovery of at least 75%. The fastener bands  104  are composed of a synthetic resin such as, polypropylene, polyethylene terephthalate (PET), polyethylene, nylon and polyvinyl chloride (PVC), among others. The fastener bands are attached to the elastic layer by thermal fusion generated by ultrasonic or thermal welding.  
         [0075]    In the embodiment of FIG. 1D, the fastener bands  104  have a backing layer  110  attached to a surface of the base layer  108  opposite the surface with the fastener elements  106 . The backing layer  110  is composed of a resin that facilitates the fusion between the base layer  108  and the elastic layer  102 . In some instances, the backing layer  110  is an adhesive that bonds the base layer  108  to the elastic layer  102 .  
         [0076]    Referring to FIGS. 2 and 2A, a stretchable fastener  100  features spaced apart bands of fastener tape  104 , attached to a sheet-form elastic substrate  102 . Each fastener band has rows  105  of fastener elements  106  integral with a base layer  108  (FIG. 2A). The fastener elements  106  are in the form of J-hooks and extend in rows  105  perpendicular to the stretching direction  112 . The J-hooks have a stem  114  and a hook shaped head  116  (FIG. 1B) pointing in the direction of the arrows (FIG. 1C) and parallel to the stretching direction  112 .  
         [0077]    Referring to FIGS. 9B and 9C, a stretchable fastener  100  features spaced apart fastener tape bands  80 , joined together by bands of an elastic substrate  88 . The elastic substrate bands  88  have edge margins  89  overlapping (FIG. 9B) or abutting (FIG. 9C) edge margins  87  of the fastener bands  80 . Each fastener band  80  has rows  72  of fastener elements  106  integral with a base layer  108  (FIG. 2A). The fastener elements  106  are in the form of J-hooks and extend in rows  72  perpendicular to the stretching direction  112 .  
         [0078]    The products of FIGS. 1 and 2 may be economically formed by the process and apparatus illustrated in FIG. 3. A sheet-form fastener  200 , supplied by roll  208 , is slit by slitter  210  to form fastener tape bands  202  extending in a longitudinal direction. The slit fastener bands  202  subsequently pass through a separator  221 . Separator  221 , separates the slit fastener bands  202  and spaces them apart transverse to a machine direction  60 . The spaced apart fastener bands are then introduced into spaced apart channels  232  formed on the surface of the channeled roll  230  (FIGS. 3A and 3B). The hook-shaped fastener elements  106  have relatively stiff stems with greater cross-section than the loop-engageable hooks and reside in the channels  232 . The hooks of the fastener elements of a given band engage the bottom of the respective channel  232 . The channels  232  have a width equal to the fastener band width w 1  and are spaced apart by a distance equal to the fastener band spacing w 2 . The fastener bands travel around a segment of the periphery of the channeled roll  230  and are introduced into a nip  242 , formed between the channeled roll  230  and a heated pressure roll  250 . Simultaneously with the fastener bands, a sheet-form elastic web  240  is introduced into the nip  242 . The heated roll presses and fuses the elastic web  240  onto the back surface of the fastener bands  202 . The hooks engaging the bottom of the channels  232  are collectively self-supporting under the pressure of laminating and assist in producing the laminating pressure by which the bands are joined to the second material. The composite elastic web with the attached fastener bands  100  is then removed from the heated roll  250 .  
         [0079]    As illustrated in FIG. 3D, the method and apparatus described above with reference to FIG. 3 can be modified to remove separator  221 . Sheet-form fastener  200 , after being slit by slitter  210  to form fastener tape bands  202  passes through tensioning nip rolls  211 ′ and  212 ′ where selected tape bands  202 ′ are directed to channeled roll  220  while tape bands  202 ″ adjacent to selected tape bands  202 ′ are directed to another channeled roll  220 ′. The processing of each set of tape bands  202 ,  202 ′ then proceeds in a similar manner to that described above, except the two sets of tape bands  202 ′,  202 ″ are processed in parallel. Accordingly, elastic film is provided by two respective film stretchers  244 ,  244 ′ and lamination is carried out by two respective heated rolls  250 ,  250 ′ that form respective nips  242 ,  242 ′ with channeled rolls  220 ,  220 ′. The parallel processing yields two completed elastic fastener products  100 ,  100 ′.  
         [0080]    While the example illustrated in FIG. 3D illustrates simultaneous production of two elastic fastener products, similar arrangements with three or more sets of apparatus for parallel processing of a corresponding sets of spaced bands can also be achieved.  
         [0081]    Referring to FIGS. 4 and 4A, the separator  221  has spaced apart openings  222  and is configured to receive the adjacent slit fastener bands  1  to  5  and place each one in a separate opening. There are at least as many openings as the number of slit fastener bands and each opening has a width at least equal to the fastener band width w 1 . The spacing w 2  between openings  222  corresponds to the desired spacing of the fastener bands  202  in the stretchable fastener  100 . By passing though the spaced apart openings, fastener bands  1  to  5  are separated and exit the separator  221  spaced apart at a distance w 2 .  
         [0082]    In the embodiment shown in FIGS. 4B and 4C, the separator  221  is configured to separate incoming slit bands  1  to  5  by removing every other band, i.e., bands  2  and  4  are removed and bands  1 ,  3  and  5  exit the separator spaced apart by a distance w 2  corresponding to the width of the removed bands. Bands  2  and  4  are introduced into openings  224 , formed in the separator  221 . Openings  224  are oriented perpendicular to the machine direction and direct bands  2  and  4  toward the recycling bin. Alternatively, the two sets of spaced apart bands, i.e., a first set formed by bands  1 ,  3 , and  5  and a second set formed by bands  2  and  4 , are each directed to a laminating apparatus and two fastener products are simultaneously produced, as discussed above with reference to FIG. 3D.  
         [0083]    The stretchable fastener of FIG. 1 may also be formed by the process and apparatus illustrated in FIG. 5.  
         [0084]    Extruder barrel  42  melts and forces molten plastic  40  through a slot-form die  41 . The extruded plastic enters nip  44  formed between base roll  48  and mold roll  46 . Mold roll  46  contains cavities  45  shaped to form hook-type fastener elements. The hook cavities  45  (FIG. 5A) are arranged in separated bands  50  on the surface of the mold roll  46  (FIG. 5B). Smooth bands  51  that contain no cavities separate the hook cavity bands  50 . The width of the cavity bands  50  equals the width of the fastener tape bands w 1  and the width of the smooth bands  51  equals the desired spacing between the fastener tape bands w 2 . The sheet-form fastener material  70  (FIG. 6A) formed in nip  44  has rows of hook fastener elements integrally molded with a base layer alternating with rows of only the base layer. The fastener material  70  travels about a segment of the periphery of mold roll  46  to slitting roll  210 . Slitting roll  210  slits and removes the bands of only the base layer  76  thus forming spaced apart bands of fastener tape  80  (FIG. 6B) having fastener elements residing in the hook molds of the mold roll  46 . A second extruder  52  introduces molten plastic  50 , suitable for molding an elastic web, through a slot-form die  51  into a nip  54  formed diametrically opposite nip  44  between the mold roll  46  and a third roll  52 . Molten plastic  50  is squeezed down to a thin film  102  and is applied to the back surface  84  of the fastener bands  80  on the mold roll  46  and fills the empty spaces  82  between the fastener bands. The back surfaces of the spaced apart fastener bands  82  fuse together with the continuous thin film  102  by the heat and pressure generated between the mold roll  46  and roll  52 . The formed composite elastic web with the attached fastener bands  100  (FIG. 6C) is subsequently removed from the third roll  52 .  
         [0085]    For more detail about the general operation of the in situ molding apparatus of FIG. 5, the reader is referred to U.S. Pat. No. 5,260,015 to Kennedy, et al., which discloses laminates made with loop materials.  
         [0086]    The stretchable fastener of FIG. 1 may also be formed by the embodiment illustrated in FIG. 7. Extruder barrel  42  melts and forces molten plastic  40  through a slot-form die  41 . The extruded plastic enters the nip  44  between base roll  48  and mold roll  46 . The entire outside surface of the mold roll  46  contains cavities  45  shaped to form hook-type fastener elements. The sheet-form fastener material  70  (FIG. 7B) formed in nip  44  has rows of hook fastener elements  106  integrally molded with a base layer  74 . The fastener material  70  travels about the periphery of mold roll  46  and is guided by two guide rolls  56  and  58  to slitting rolls  210 . Slitting rolls  210  slit the fastener  70  into bands  80  which are then separated by passing through separator  221 . The spaced apart fastener bands  80  are then introduced into spaced apart channels  232  formed on the surface of the channeled roll  230  (FIG. 7C). The hook-shaped fastener elements  106  reside in the channels  232  with the hooks engaging the bottom of the respective channel. The channels  232  have a width equal to the fastener band width w 1  and are spaced apart by a distance equal to the fastener band spacing w 2 . The fastener bands are introduced into a nip  242 , formed between the channeled roll  230  and a heated pressure roll  250 . Simultaneously with the fastener bands, a sheet-form elastic web  240  is introduced into the nip  242 . The heated roll  250  presses and fuses the elastic web  240  onto the back surface  84  of the fastener bands  80 . The hooks engaging the bottom of the channels  232  are collectively self supporting under the pressure of laminating and assist in producing the laminating pressure by which the bands are joined to the second material. The composite elastic web with the attached fastener bands  100  is then removed from the heated roll  250 .  
         [0087]    In the embodiment of FIG. 9, separated fastener bands  80  are formed directly on the mold roll  46  by using a die  41  that has multiple spaced apart slots  43  (FIG. 8). Mold roll  46  contains cavities  45  shaped to form hook-type fastener elements, and the hook cavities  45  (FIG. 5A) are arranged in separated bands  50  on the surface of the mold roll  46  (FIG. 5B). Slots  43  are aligned to inject molten resin into the cavity bands  50  of the mold roll  46 , have a width equal to the fastener band width w 1 , and are spaced apart by a distance equal to the spacing between the fastener tape bands w 2 . A second slotted die  51  with multiple slots is used in the second extruder  52  to form bands of elastic film  88  filling the spaces  82  between the fastener tape bands  80  (FIG. 9B). The edge margins  89  of the bands of elastic film  88  overlap the edge margins  87  of the fastener bands  80 . In some embodiments (FIG. 9C), the edge margins  89  of the bands of elastic film  88  abut the edge margins  87  of the fastener bands  80 .  
         [0088]    In the embodiment of FIG. 10, the bands of elastic film  88  are coextruded with the bands of the fastener tape  80  by using an extruder with separate chambers  42  and  52  and two separate slotted dies  41  and  51  connected to the separates chambers  42  and  52 , respectively (FIG. 10B). The two slotted dies  41  and  51  have multiple slot openings  41   a  to  41   c  and  5 l a  to  51   d , respectively (FIG. 10A). Two different types of molten resin are simultaneously extruded into the same nip  44 . The coextruded bands of fastener tape  80  and elastic film  88  are fused at the margins  89  and  87  by the pressure and heat provided by roll  48 .  
         [0089]    Other features and advantages of this invention may include one or more of the following. A continuous heated belt may be used to apply pressure and heat to the elastic web to cause fusion to the back surface of the fastener bands. Elastic webs having an elongation of at least 300% and recovery of at least 75% may be used. The width of the fastener bands may be between ⅛ to ¼ inch (3.18 to 6.35 mm). The width of the elastic bands may be between ⅛ to ¼ inch (3.18 to 6.35 mm). Narrow fastener bands separated by narrow elastic bands are used to form stretchable fasteners covering a large area. Large area stretchable fasteners may be used to form stretchable bands that provide motion flexibility. A wide stretchable fastener band  18  next to a wide elastic band  19  may be used to form a fastener tab  12  used as part of infant and adult diapers  10  (FIGS. 11 and 11A).  
         [0090]    Although each of the above-described examples has referred to hook-shaped fastener elements, any shape suitable for engaging a loop or mesh material, or capable of engaging other fastener elements of like or unlike shape is suitable. For example, co-pending U.S. Ser. No. 09/231,134, the full contents of which are hereby incorporated by reference, discloses various suitable fastener elements and methods and apparatus for their manufacture. Briefly, referring to FIG. 12, one example of an alternative fastener shape is fastener element  10  which includes a base  12  and a fastener element  14  extending from the base. (Fastener  10  generally includes an array of fastener elements; a single fastener element is shown for clarity.) Fastener element  14  includes a stem  16  and, at the terminal end of stem  16 , a head  18 . Head  18  is shaped for engagement with another fastener component, for example a female fastener component having a plurality of loops, a mesh such as an insect screen, or another fastener component similar to fastener  10 .  
         [0091]    As shown in FIG. 12, head  18  is substantially disc-shaped, including a substantially planar top surface  20 , and a substantially planar bottom surface  22  that faces and overhangs base  12 . It is desirable that the disc be relatively thin, allowing a cooperating fastener element, e.g., a loop or the wire mesh of a window screen, to penetrate into the disc by flexing the disc material. Preferably, the thickness of the disc is from about 5 to 15% of the equivalent diameter of the disc. If the disc is thinner, it will tend to have reduced cycle life (i.e., durability during repeated engagement and disengagement of the fastener), whereas if the disc is thicker the fastener may exhibit reduced peel strength.  
         [0092]    A machine  300  for forming the fastener elements  10  described above is shown in FIG. 13. For a more detailed description the reader is again referred to previously incorporated U.S. Ser. No. 09/231,134. Briefly, a supply roll  302  introduces a continuous supply of a stem-carrying base  12  (FIG. 12) into the machine  300 . Stem-carrying base  12  is formed of a thermoformable polymer. In a previous manufacturing step, roll  302  was wound up as the take-up roll at a molding station (not shown, but one example of a stem molding method is similar to the hook molding operation described above with reference to FIGS. 5 and 7 wherein the mold cavities have a straight stem shape instead of a hook shape) at which stems were integrally molded onto base  12 . Alternatively, as discussed further below, the stem-carrying base  302  has already been slit, separated and joined to an elastic web using, e.g., one of the methods and apparatus previously described with reference to FIGS. 3, 3D,  5 ,  7  or  9 .  
         [0093]    The supply roll  302  is unwound by drive mechanism  306 , which conveys stem-carrying base  12  into optional pre-heating area  308  which raises the temperature of the stem-carrying base  12  to a pre-heat temperature that is above room temperature but much lower than the temperature at which the polymer melts or deforms. This pre-heating allows the tips of the stems to be heated to a predetermined softening temperature more quickly during the next step of the process.  
         [0094]    Next, the base  12  moves to heating device  310 , which heats only a distal portion, i.e., a portion furthest from base  12 , of the stems. The remainder of the stem remains relatively cool and thus relatively rigid. The distal portion is heated to a softening temperature at which it can be formed into a desired head shape. To ensure that only the distal portion of each stem is heated to the softening temperature, it is preferred that heating device  310  include a non-contact heat source that is capable of quickly elevating the temperature of material that is very close to the heat source, without raising the temperature of material that is relatively further away from the heat source. Suitable non-contact heat sources include flame heaters, electrically heated nichrome wire, and radiant heater blocks. To heat the distal portion to the softening temperature without contact, the heat source typically must be at a relatively high temperature. For example, if the softening temperature is from about 100 to 140° C., the temperature of the heat source will generally be from about 300 to 1000° C. and the heat source will be positioned from about 0.1 to 30 mm from the tips of the stems.  
         [0095]    After the distal portions of the stems have been heated, the base  12  moves to conformation head  312 , at which base  12  passes between conformation roll  314  and drive roll  316 . Conformation roll  314  forms the distal portion of the stems into a desired head shape, as will be described in further detail below, while drive roll  316  advances base  12  and flattens it against roll  314  to enhance head uniformity. It is preferred that the temperature of conformation roll  314  (the forming temperature) be lower than the softening temperature. Maintaining the conformation roll  314  at this relatively low temperature has been found to allow the conformation roll to flatten the spherical (“ball-shaped”) heads that are generally formed during the previous heating step into a desired head shape. Spherical heads are generally undesirable, as such heads tend not to provide secure engagement with a mating fastener. A low forming temperature also prevents adhesion of the thermoformable polymer to the conformation roll. Generally, to obtain the desired forming temperature it is necessary to chill the conformation roll, e.g., by running cold water through a channel in the center of the roll, to counteract heating of the conformation roll by the heat from the distal portions of the stems. If further cooling is needed to obtain the desired forming temperature, the drive roll may be chilled in a similar manner.  
         [0096]    The surface texture of conformation roll  314  will determine the shape of the heads that are formed. If disc-shaped heads having a smooth surface (as illustrated in FIG. 12) are desired, the surface texture will be smooth and flat. If a sandpaper-like surface is desired, the surface texture of the conformation roll will be sandpaper-like. If mushroom-shaped (domed) heads are desired, the conformation roll will include a plurality of substantially hemispherical indentations (“dimples”) to form the dome portion of the heads. Other shapes are of course possible by using a conformation roll with a surface shape corresponding to the desired fastener head shape.  
         [0097]    The spacing of the conformation roll  314  from the drive roll  316  is selected to deform distal portions of the stems to form the desired head shape, without excessive damage to the unheated portion of the stems. It is also preferred that the spacing be sufficiently small so that the drive roll flattens base  12  and provides substantially uniform contact pressure of the stem tips against the conformation roll. Preferably, the spacing is approximately equal to the total height of the stem less the length of the heated distal portion.  
         [0098]    Next, the base  12  moves to a cooling station  318 . Cooling station  318  cools the formed heads, e.g., by cool air, preventing further deformation of the heads. Preferably, the heads are cooled to approximately room temperature. The cooled base is then moved through driving station  320  and is then passed through a slitter  322 , a separator  324 , and a joining station  326  where separated bands of the product are joined to an elastic web. Slitter  322 , separator  324 , and joining station  326 , can be apparatus similar to those described above, e.g., with reference to FIGS.  3  or  3 D, and operate in a similar manner.  
         [0099]    In an alternative arrangement, a base having stems only, is formed, slit and joined to a stretchable web as described above with reference to FIGS. 3, 3D,  5 ,  7 , and  9 , and the stems are later formed into a fastener shape as described above with reference to FIGS. 12 and 13. The resulting fastener product  100 ′ is similar to that shown, e.g., in FIGS.  1 - 1 D but having fastener elements similar to that illustrated in FIG. 12.  
         [0100]    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. Accordingly, other embodiments are within the scope of the following claims.