Abstract:
A tough low set elastic film exhibiting surprisingly high tear resistance and method of making the same. The film of the invention is especially beneficial when holes form on the films during manufacturing or normal wear and method of making. The film has activated and non-activated zones formed during an activation process. The activated zones allow the film to expand without generating excessive tensional forces. The film has M-polypropylene or M-polyethylene skin layers and a core layer having an elastomeric polyurethane, ethylene copolymer such as ethylene vinyl acetate styrenic elastomer, an ethylene/propylene copolymer elastomer or ethylene/propylene/diene terpolymer elastomer. The activation process allows the skin layers to behave more like the core layer.

Description:
BACKGROUND 
     The present invention relates to elastic films, and more particularly, to elastic films having high tear-strength and low set. Elastic films of the present invention having high tear-strength and low set exhibit surprisingly high tear resistance, especially when holes form on the films. 
     Elastic films of the present invention have a wide range of potential uses in both durable and disposable articles, but are particularly well suited for use in elastic waistbands and in products including absorbent products and the like. 
     SUMMARY OF THE INVENTION 
     The present invention relates to the coextrusion of a thin multi-layer elastic film that stretches in the transverse direction. The elastic film has a first layer, a second layer and a core layer. The film has activation zones and non-activated zones. The activated zones have sufficient elasticity to stretch to at least 200% while maintaining a permanent set percent of no more than 5%. The non-activated zones have sufficient non-elastic to stretch at least 200% while maintaining a permanent set percent of up to 5%. The activated zones have a tear strength as measured by the Elmendorf Tear Test of 30 g while the non-activated zones have a tear strength as measured by the Elmendorf Tear Test of at least 50 g. The elastic film is particularly useful as an elastic waistband for use in products including absorbent products such as waist bands, side panels and the like. The superior tear-strength of the film prevents tearing during use of the film and promotes longer-lasting applications of the film., In addition, the superior tear-strength of the film prevents existing tears from propagating throughout the film. For ease of illustration, a thin multi-layer coextruded elastomeric film is described in detail herein in FIGS. 1-7. However, this detailed description will allow those skilled in the art to adapt this invention to produce elastomeric film for other applications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged cross-section of the film in the present invention. 
     FIG. 2 is a top plan view of a textured surface of the film of FIG. 1 showing activated zones and non-activated zones. 
     FIG. 3 is a simplified schematic illustration showing the embossed stretch film forming process of the present invention. 
     FIG. 4 is a simplified schematic illustration showing the activation process of the present invention. 
     FIG. 5 is an enlarged side view of the lower disk assemblies used to activate the film of FIG. 1 during the activation process of FIG.  5 . 
     FIG. 6 is an enlarged cross-section of the film of FIG. 1 showing the undulations of the activated zones of the film. 
     FIG. 7 is an enlarged cross-section of the film of FIG. 1 showing the peaks and valleys of the non-activated zones of the film. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures, and in particular FIG. 1, FIG. 6, and FIG. 7, there is shown an enlarged cross-section of a film  100 . The film  100  is a textured film with a smooth surface  101  and a textured surface  102 . The textured surface  102  has texture peaks  103  and texture valleys  104 . The film  100  includes activated zones  105  and non-activated zones  106 . In one embodiment, the textured surface  102  is an embossed surface. The film  100  includes a first layer  110 , a core layer  120  and a second layer  130 . The core layer  120  has first core layer surface  121  and a second core layer surface  123 . The first layer  110  includes a first layer inner surface  115  adjacent to the first core layer surface  121 , and a first layer outer surface  111  which forms the smooth surface  101  of the film  100 . The second skin layer  130  includes a second layer inner surface  135  adjacent to the second core layer surface  123  and a second layer outer surface  131  which forms the textured surface  102  of the film  100 . The activated zones  105  of the film  100  have undulations  113  and  133  in the first skin layer  110  and the second skin layer  130 , respectively. 
     The core layer  120  is a highly-elastic compound, such as a compound involving at least one or more block copolymers with a hydrogenated diene from the type A-B-A or A-B-A′. Usually such a compound exhibits relatively good elastic recovery or low set from stretching over 100 percent when extruded alone as a single layer. Styrene/isoprene, butadiene or ethylene-butylene/styrene (SIS, SBS, or SEBS) block copolymers are particularly useful. Other useful elastomeric compositions for use as a core layer  120  can include elastomeric polyurethanes, ethylene copolymers such as ethylene vinyl acetates, ethylene/propylene copolymer elastomers or ethylene/propylene/diene terpolymer elastomers. Blends of these polymers alone or with other modifying elastic or non-elastomeric materials are also contemplated as being useful with the present invention. In certain preferred embodiments, the elastomeric materials can comprise such high performance elastomeric material such as Kraton® elastomeric resins from the Shell Chemical Co., which are elastomeric block copolymers. In one embodiment, the film comprises a skin/core/skin weight percentage of 10/80/10 polypropylene skin layer, Kraton® elastomeric resin core layer, and polypropylene skin layer. For applications requiring a thicker film, a skin/core/skin of 15/70/15 percentage by weight may be used. A thicker film may be used advantageously for the following reasons: the film. is less expensive due to the lower percentage of the expensive elastomeric core; a thicker skin allows drawing the film thinner without encountering draw resonance during extrusion; and a thicker skin increases the tear strength of the film as supported in the Tables below. 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 ELASTIC FILM PROPERTIES 
               
             
          
           
               
                   
                   
                 FILM 
                   
                 FILM 
                   
                 FILM 
                   
               
               
                 Description: 
                 FILM 1 
                 1A 
                 FILM 2 
                 2A 
                 FILM 3 
                 3A 
                 FILM 4 
               
               
                   
               
             
          
           
               
                 Basis Weight 
                 g/m 2   
                 77.1 
                 68.4 
                 60 
                 53.0 
                 70.7 
                 45.4 
                 68.6 
               
               
                 Emb. Caliper, (2″) 
                 mils 
                 4.17 
                 3.59 
                 3.18 
                 2.83 
                 4.06 
                 10.18 
                 3.7 
               
               
                 MD Tens. @ 10% 
                 grams 
                 385 
                 529 
                 268 
                 301 
                 688 
                 584 
                 494 
               
               
                 MD Tens @ 25% 
                 grams 
                 561 
                 610 
                 421 
                 374 
                 975 
                 640 
               
               
                 MD Tens @ Break 
                 grams 
                 5681 
                 5448 
                 3899 
                 2139 
                 5899 
                 3590 
                 4621 
               
               
                 MD Elongation 
                 % 
                 725 
                 696 
                 705 
                 546 
                 718 
                 716 
                 773 
               
               
                 TD Tens. @ 10% 
                 grams 
                 323 
                 101 
                 207 
                 52 
                 494 
                 113 
                 54 
               
               
                 TD Tens. @ 25% 
                 grams 
                 448 
                 162 
                 298 
                 91 
                 673 
                 194 
                 3653 
               
               
                 TD Tens. @ Break 
                 grams 
                 5346 
                 3920 
                 3160 
                 2785 
                 4952 
                 3695 
                 753 
               
               
                 TD Elongation 
                 % 
                 829 
                 631 
                 767 
                 696 
                 741 
                 390 
               
               
                 C.O.F. (Mat&#39;l/Mat&#39;l) 
                 Index 
                 .49/.58 
                 .79/.57 
                 1.30/2.67 
                 .75/.95 
                 1.04/1.78 
                 .88/.94 
                 .86/.75 
               
               
                 Opacity 
                 % 
                 91.1 
                 86.3 
                 84.3 
                 79.2 
                 73.5 
                 64.2 
                 74.2 
               
             
          
           
               
                 100% TD Cyclic 
                   
                 None 
                 350% 
                 None 
                 None 
                 350% 
                 None 
                 None 
                 350% 
                 None 
                   
               
               
                 1st Load @ 25% Elong. 
                 grams 
                 442 
                 123 
                 170 
                 294 
                 73 
                 89 
                 654 
                 282 
                 193 
                 161 
               
               
                 1st Load @ 50% Elong. 
                 grams 
                 489 
                 165 
                 217 
                 342 
                 104 
                 117 
                 726 
                 394 
                 255 
                 195 
               
               
                 1st Load @ 75% Elong. 
                 grams 
                 512 
                 201 
                 243 
                 362 
                 128 
                 134 
                 762 
                 741 
                 323 
                 220 
               
               
                 1st Load @ 100% Elong. 
                 grams 
                 524 
                 238 
                 267 
                 371 
                 158 
                 150 
                 783 
                 1202 
                 421 
                 250 
               
               
                 1st Unload @ 25% 
                 grams 
                 3 
                 24 
                 67 
                 1 
                 24 
                 46 
                 1 
                 23 
                 44 
                 62 
               
               
                 1st Unload @ 50% 
                 grams 
                 111 
                 65 
                 117 
                 70 
                 52 
                 75 
                 128 
                 118 
                 93 
                 101 
               
               
                 1st Unload @ 75% 
                 grams 
                 226 
                 105 
                 154 
                 156 
                 75 
                 96 
                 305 
                 236 
                 153 
                 135 
               
               
                 1st Unload @ 100% 
                 grams 
                 420 
                 196 
                 224 
                 299 
                 133 
                 131 
                 620 
                 907 
                 335 
                 209 
               
               
                 Column Number 
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                 2nd Load @ 25% Elong. 
                 grams 
                 188 
                 93 
                 129 
                 100 
                 60 
                 74 
                 232 
                 186 
                 135 
               
               
                 2nd Load @ 50% Elong. 
                 grams 
                 333 
                 140 
                 183 
                 223 
                 91 
                 103 
                 483 
                 306 
                 196 
               
               
                 2nd Load @ 75% Elong. 
                 grams 
                 433 
                 181 
                 216 
                 305 
                 117 
                 122 
                 645 
                 576 
                 266 
               
               
                 2nd Load @ 100% 
                 grams 
                 512 
                 231 
                 252 
                 368 
                 154 
                 143 
                 775 
                 1190 
                 395 
               
               
                 2nd Unload @ 25% 
                 grams 
                 −1 
                 22 
                 65 
                 0 
                 23 
                 45 
                 2 
                 21 
                 43 
               
               
                 2nd Unload @ 50% 
                 grams 
                 105 
                 65 
                 116 
                 67 
                 51 
                 73 
                 122 
                 120 
                 93 
               
               
                 2nd Unload @ 75% 
                 grams 
                 226 
                 106 
                 153 
                 158 
                 75 
                 94 
                 312 
                 240 
                 153 
               
               
                 2nd Unload @ 100% 
                 grams 
                 425 
                 196 
                 220 
                 306 
                 134 
                 129 
                 636 
                 927 
                 333 
               
               
                 1st Cycle Relaxation 
                 % 
                 19.9 
                 17.7 
                 16.0 
                 19.4 
                 16.2 
                 12.7 
                 20.8 
                 24.5 
                 20.3 
                 16.2 
               
               
                 2nd Cycle Relaxation 
                 % 
                 17.2 
                 15.1 
                 12.7 
                 16.9 
                 13.0 
                 9.5 
                 18.0 
                 22.1 
                 15.7 
                 13.5 
               
               
                 Hysteresis 
                 % 
                 2.2 
                 3.1 
                 5.4 
                 1.0 
                 2.7 
                 5.0 
                 1.1 
                 1.0 
                 6.2 
                 5.0 
               
               
                 Permanent Set 
                 % 
                 13.8 
                 4.3 
                 2.7 
                 15.0 
                 2.7 
                 2.6 
                 16.6 
                 8.4 
                 3.0 
                 1.7 
               
               
                 Column Number 
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Elastic Film Properties: Toughness Measures 
               
             
          
           
               
                   
                 P.1 
                 P.2 
                 1. 
                 1. PS 
                 1. Act. 
                 2. 
                 2. PS 
                 2. Act. 
                 3. 
                 3. PS 
                 3. Act. 
                 4. 
                 4. PS 
                 4. Act. 
               
               
                   
                   
               
             
          
           
               
                 Activation 
                 N/A 
                 N/A 
                 N/A 
                 39% 
                 10-15% 
                 N/A 
                 58% 
                 10-15% 
                 N/A 
                 72% 
                 10-15% 
                 N/A 
                 72% 
                 10-15% 
               
               
                 Growth 
               
             
          
           
               
                   
                 Prior Art 
                 First Sample Set 
                 Second Sample Set 
               
             
          
           
               
                 TD @ 25%, g 
                 154 
                 154 
                 435 
                 107 
                 158 
                 340 
                 94 
                 137 
                 561 
                 293 
                 250 
                 415 
                 206 
                 153 
               
               
                 TD @ 25%, g 
                 151 
                 154 
                 437 
                 122 
                 247 
                 324 
                 83 
                 105 
                 528 
                 264 
                 247 
                 394 
                 183 
                 143 
               
               
                 TD Ultim., g 
                 1680 
                 2452 
                 4180 
                 5073 
                 2991 
                 3035 
                 3148 
                 3054 
                 5366 
                 5285 
                 5001 
                 3544 
                 4032 
                 3496 
               
               
                 TD Ultim., g 
                 1294 
                 1419 
                 1900 
                 1185 
                 1783 
                 1123 
                 653 
                 951 
                 1905 
                 988 
                 1757 
                 1509 
                 801 
                 1248 
               
               
                 TD Elg., % 
                 756 
                 813 
                 747 
                 527 
                 628 
                 751 
                 404 
                 646 
                 800 
                 400 
                 659 
                 776 
                 410 
                 659 
               
               
                 TD Elg., % 
                 667 
                 618 
                 587 
                 322 
                 425 
                 527 
                 200 
                 455 
                 524 
                 161 
                 431 
                 542 
                 169 
                 416 
               
               
                 TD Ult/TD25 
                 10.9 
                 15.9 
                 9.6 
                 47.4 
                 18.9 
                 8.9 
                 33.5 
                 22.3 
                 9.6 
                 18.0 
                 20.0 
                 8.5 
                 19.6 
                 22.8 
               
               
                 TD Ult/TD25 
                 8.6 
                 9.2 
                 4.3 
                 9.7 
                 7.2 
                 3.5 
                 7.9 
                 9.1 
                 3.6 
                 3.7 
                 7.1 
                 3.8 
                 4.4 
                 8.7 
               
               
                 Bas. Wt., gsm 
                 50.7 
                 50.2 
                 73.5 
                 N/A 
                 61.4 
                 63.0 
                 N/A 
                 46.2 
                 76.0 
                 N/A 
                 68.2 
                 61.1 
                 N/A 
                 56.7 
               
               
                 MD Tear, g 
                 15 
                 18 
                 156 
                 N/A 
                 68 
                 90 
                 N/A 
                 54 
                 256 
                 N/A 
                 284 
                 138 
                 N/A 
                 128 
               
               
                   
               
               
                 The First Sample Set material was made of 10/80/10 coextrusion layering and activated 350% in the prestretch and disk assembly activation, the Second Sample Set material was 15/70/15 and activated 250% in prestretch and disk activation.  
               
             
          
         
       
     
     The first layer  110  and the second layer  130  are polyolefins, and can comprise a blend of polyethylene with Metallocene-catalyzed polyethylene (m-polyethylene) or Metallocene-catalyzed polypropylene (m-polypropylene). If the blends are extruded as a single layer, the blends exhibit poor elastic recovery or high set from stretching over  100  percent. FIG. 2 is a top plan view of the textured surface  102  of the film  100  showing the activated zones  105  and non-activated zones  106 . In addition, the textured pattern may be visible over the entire textured surface  102  of the film  100 . As can be seen from FIG. 2, the undulations  113  in the activated zones  105  of the second layer  130  form uniform uni-directional parallel marks in the machine direction in the textured surface  102  of the film  100 . 
     The film  100  has a high coefficient of fiction (COF). It is desirous to have such a high COF to enable successful gripping of the film  100  for stretching and placement in subsequent converting. This is due in part to the non-activated zones  106  remaining non-activated despite stretching the film  100  up to 200%. This property enables the film  100  to exhibit low percent set comparable to the highly elastic core layer  120  while maintaining a coefficient of friction comparable to a polyolefin elastomeric film. Other films often require a slip additive, which results in a lower COF. The slip additive prevents the films from sticking during film collection and dispension. Unfortunately, the slip additive and resulting lower COF hinders the mechanical or vacuum-assisted stretching process. 
     FIG. 3 is a simplified block diagram illustrating a forming process  200  for forming the embossed stretch film  100  of the invention. A cast coextrusion  11  of the skin/core/skin exits coextruder  210  through coextrusion slot die  211 . Prior to hardening, cast coextrusion  11  is delivered at an elevated temperature as a molten or semi-molten plastic to an engraved roll  220 . In certain embodiments, the cast coextrusion  11  exits the coextruder  210  at a temperature of about 350° F. to about 650° F. (175° C. to 315° C.). The melt temperature of the polymer resin is about 400° F. to about 475° F. The embossed coextrusion  12  is then collected onto embossed film roll  240 . Engraved roll  220  has a smooth surface  221  which engages cast coextrusion  11  and moves cast coextrusion  11  into contact point  222  of backup roll  230 . Backup roll  230  has embossing surface  231  for delivering an embossed pattern to emboss the cast coextrusion  11  forming an embossed coextrusion  12 . 
     In the embodiment shown, the cast coextrusion  11  is preferably extruded through the slot die  211  at a distance of about 1 to about 10 inches, and most preferably about 2 to about 6 inches, from engraved roll  220 . The pressure between the backup roll  230  and engraved roll  220  causes the embossed coextrusion  12  to retain the embossed pattern from the embossing surface  231 . The engraved roll  220  or the backup roll  230  can be temperature controlled to add heat or cooling of the polymer resin as desired. However, it is to be understood that other temperature control means can be used to adjust the temperature of the polymer resin at this point. 
     As illustrated in FIG. 3, the film  100  is formed without the use of adhesives. The lowest melting layer of the cast coextrusion  11  is molten or semi-molten, which means that the thermoplastic melt stream of the elastomeric film material is at a temperature above the temperature of melting (T m ) of the thermoplastic film material. The temperature of melting of polymers is determined on a differential scanning calorimeter. When the polymer stream is in the molten or semi-molten phase, the polymer is amorphous; that is, molecules comprising the elastomeric polymer are free to move about, particularly when influenced by outside forces such as a pressure differential. Portions of the embossed coextrusion  12  that form the textured surface  102  of the film  100  retain the embossed pattern due to the pressure differential between the backup roll  230  until the cast coextrusion  11  at least partially sets or crystallizes. At that time, the embossed coextrusion  12  is no longer formable and retains its new shape. This phase is known as the temperature crystallinity (Tc) and is also determined by a differential scanning calorimeter. After the cast coextrusion  11  is embossed, the cast coextrusion  11  releases enough heat energy to move below the temperature of crystallinity while still being held in its new (embossed coextrusion  12 ) shape by the pressure differential. 
     As described herein, the final film  100  is embossed. However, instead of a backup roll  230 , an air knife (not shown), wherein air is blown onto the cast coextrusion  11  prior to the contact point  222 , may be used to quench the cast coextrusion  11  without an embossed pattern. This may draw the cast coextrusion  11  thinner and thereby reduce manufacturing costs. Alternatively, a vacuum box (not shown) may be placed inside engraved roll  220  to draw the cast coextrusion  11  over the surface of the engraved roll  220  and quench the molten web. The embossed pattern as described herein penetrates into the cast coextrusion at a depth of about 1.5 to 2.5 mils. The backup roll  230  has a temperature control for controlling how quickly the film  100  cools. In the forming process  200 , the temperature of the backup roll  230  is preferably in the range of 90° F. to 140° F. If the cast coextrusion  11  is allowed to cool too slowly, the cast coextrusion  11  may become brittle. In the preferred embodiment, the embossed coextrusion  12  has an embossed maximum width of about 6 mils. 
     It is to be understood that there are elastomeric polymers with different melt temperatures and that the distance between the coextrusion slot die  211  and the contact point  222  can be varied based on the parameters defined by the use of a particular polymer. Thus, the contact point  222  of the film  100  will depend on the melting temperature of the specific polymer in use at the time. 
     Referring now to FIG. 4, an activation process  250  is shown. The embossed coextrusion  12  is fed from the embossed film roll  240  through parallel disk assemblies  260 . The embossed coextrusion  12  is then collected onto the activated film roll  290 . 
     In the embodiment shown, an upper disk assembly  270  includes circumferentially spaced ridges  271 . Ridges  271  have an engagement height  272  and an engagement width  273 . Ridges  271  are equally spaced along the circumference of upper disk assembly  270 . Lower disk assembly  280  opposes upper disk assembly  270 . Lower disk assembly  280  includes ridges  281  having an engagement height  282  and an engagement width  283 . Ridges  271  of upper disk assembly  270  and ridges  281  of lower disk assembly  280  are alternately spaced along the respective circumferences of assemblies  270 ,  280  such that the embossed coextrusion  12  passes through each ridge independently. Ridges  281  are equally spaced along the circumference of lower disk assembly  280 . Assemblies  270 ,  280  are shown in greater detail in FIG.  5 . In the present embodiment, as the embossed coextrusion  12  travels through ridges  271 ,  281 , the embossed coextrusion  12  is stretched and elongated and becomes corrugated onto the core layer  120  (FIG.  6 ). In certain preferred embodiments, the depth of engagement of the ridges  271 ,  281  is in the range of 165 to 230 mils, which is much deeper than conventional ridges known to be used in the art. Ridges  271 ,  281  in a preferred embodiment are 27 mils. wide and are spaced apart by 49.5 mils. While traveling through the ridges  271 ,  281 , the embossed coextrusion  12  is subjected to stretching in a way such that only small, discreet and narrow longitudinal strip regions of the embossed coextrusion  12 , not exceeding  1  inch in width, are elastically overstrained in order to significantly decrease the thickness of the skin layer in these regions compared to the thickness of the skin layers in the adjacent regions. This can be seen in more detail in FIGS. 1 and 2. The elastic overstraining occurs by applying a relatively high strain rate to extension ratio of at least 350 percent while adjacent regions located between the strips are strained from 10 percent to 200 percent. The combination of the high strain rate and the high extension causes extreme thinning of the polyolefinic elastomeric layers in the narrow strip region that were overextended. This effect, in turn, enables the activated zones  105  to behave more like core layer  120 , which will become the predominant elastomer. The resulting multi-layer film  100  exhibits elastic properties comparable to the core layer  120 , i.e., a very low percent set. Surprisingly, the film  100  exhibits an overall tear-strength value as measured by the Elmendorf Tear test well above conventional films in the art. The tear-strength of the film  100  is important during conversion of the finished film  100  to final products. Namely, when an initial cut is made on the film  100  for incorporation into a product, the cut is sometimes non-uniform and leaves jagged edges. A film having a sufficiently high tear-strength will prevent propagation of any tears that result from the initial cutting of the film. The film  100  of the present invention has a tear-strength that is much superior to conventional films used in the art. In addition to other advantages described herein, the film  100  will last much longer in applications due to the tear-resistence inherent in the film  100 . The film  100  continues to exhibit a coefficient of a friction (COF) comparable to a polyolefin elastomer film. The COF value enables the film  100  to be easily manipulated during post-formation manufacturing processes. 
     The activation process  250  may be combined with film forming process  100  to eliminate the steps of collecting the embossed coextrusion  12  and re-feeding the embossed coextrusion  12  through parallel disk assemblies  260 . In this embodiment, the embossed coextrusion  12  would proceed to the parallel disk assemblies  260  after the embossed pattern has been formed in the embossed coextrusion  12 . 
     The film  100  has several advantages. First, skin layers may be coextruded using the process of the invention that are much thinner than conventional skin layers. The thinness of the material enhances the overall elasticity of the film  100 . 
     Second, the tear-strength of the skin layers of the present invention is critical to the overall properties of the film  100 . The superior tear-strength of film  100  is required for mechanical activation of the film  100  at the very high ridge penetration depth as the film  100  passes through disk assemblies  260  during the activation process  250 . The use of a less tear-resistant film would significantly hinder mechanical activation by limiting the depth ridges  271 ,  281  are allowed to penetrate into the film  100 . Because the film  100  is exceedingly tear-resistant, the skin layers  110 ,  130  are thinner and activate readily. The film  100  may subsequently stretch with strong retractive forces and recover with very low setting. 
     Third, the film  100  is surprisingly resistant to tear propagation, which is useful in certain applications. In some applications, a user ultrasonically or by other means pits the film  100  in order to increase film breathability. During use of the application, the film  100  may be under constant or varying degrees of tension. A less tear-resistant film would not protect the areas around any pits formed prior to film usage and thus the film would be subject to increased tear propagation. The tear resistance of the present invention would sufficiently resist such propagation and extend the usefulness of the film. 
     Fourth, the skin layers  110 ,  130  have high compatibility with the core layer  120 . This allows skin layers  110 ,  130  to remain in intimate contact with the core layer  120  during activation, whereby skin layers  110 ,  130  do not separate or rupture from the core layer  120 . The thinner activated zones  105  thus retain and behave more like the highly-elastic core layer  120 . 
     Finally, the skin layers in the present invention have a sufficiently high COF comparable to polyolefin elastomeric films to allow handling of the film  100  via mechanical gripping or vacuum-assisted gripping. 
     Table 1 shows the films prior to activation through the disk assemblies  260  and post-activation by the application of the film through the disk assemblies  260 . As can be seen, the permanent set percent significantly decreases after activation. In the data set forth in Table 1 above, elastic hysteresis is used to quantify elastic performance. The high performance elastic behavior is defined by tensile set less than about 10 percent and force relaxation less than about 20 percent after 300 percent elongation. The procedure to measure hysteresis of a sample is as follows: 
     1. A sample of the film or laminate is placed. in the jaws of a tensile testing machine. 
     2. The sample is pulled a first time (cycle 1 elongation) at the rate of 20 inches per minute to the desired elongation (for example, 200 percent) 
     3. The force upon reaching the desired elongation is noted. 
     4. The sample is held at the desired elongation for 30 seconds after which the force is noted. 
     5. The instrument is returned to its initial position (zero elongation) 
     6. The sample is held in a relaxed state for 30 seconds. 
     7. The sample is pulled a second time (cycle 2 elongation) at the rate of 20 inches per minute to the desired elongation. The amount of movement in. the tensile testing machine jaw before the film exerts any force is noted. 
     8. The sample is held at the desired elongation for 30 seconds and then relaxed. 
     Tensile set is a measure of the permanent deformation of the sample as a result of the initial elongation, hold, and relax cycle. Specifically, tensile set is the elongation measured in the second cycle divided by the initial sample length (2 inches). 
     The transverse direction (TD) force at 10 percent elongation is a measure of the force required to extend the film 10 percent in the transverse (i.e., cross machine) direction. The tensile properties (TD force) were measured using the ASTMD-882 method. In the present application, the machine direction (MD) is defined as the direction in which the film is moved through the processing. The transverse (or cross machine) direction is the direction perpendicular or transverse to the machine direction. 
     Films 1 and 1A, 2 and 2A, and 3 and 3A are of identical composition. Films 1 and 1A have a modified SEBS core having a draw resonance limit of about 75 grams per square meter. Films 2 and 2A are identical except that they employ a softer grade core and have a draw resonance limit of about 60 grams per square meter. Films 3 and 3A are produced with a very low cost formulation comprising SIS and polyethylene. Film 4 has a core composed of SIS/PE having a draw resonance limit of about 69 grams per square meter. For film 1 and film 2, readings are given for no activation, and for activation using an Instron tensile tester wherein the film is elongated to 350 percent extension. As can be seen from the Table, the permanent set for the ring rolled film 1A, 2.7 percent, is significantly less than film 1, wherein the film was activated using the Instron tensile tester, resulting in a 4.3 permanent set. Likewise, the permanent set for film 2A, 2.6 percent, is less than the permanent set for film 2 activated with the tensile tester at 2.7 percent. Film 3A also showed a dramatic decrease in percent permanent set of 3.0 percent versus the percent set of the same film using an Instron tensile tester at 8.4 percent. And the lowest cost film, depicted as Film 4, showed remarkably low permanent set percent of 1.7. 
     The tear-strength of the film material, depicted in Table 2, shows properties of skin layers  110 ,  130  in comparison to conventional skin layers. An Elmendorf Tear Test was used to measure the toughness of the film. As used herein, the Elmendorf Tear Test refers to the procedure to measure the toughness of the film, and is in accordance with ASTMD 1922 method, entitled  Standard Test Method for Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method.    
     As illustrated, Table 2 depicts three sets of data: prior art samples; a first sample set of the present invention using a 10/80/10 skin/core/skin weight percentage; and a second sample set of the present invention using a 15/70/15 weight percentage. The columns are labeled in the following manner: P. 1 and P. 2 refer to prior art sample 1 and 2, respectively; 1., 1. PS, 1. Act. refer to first sample set 1 prior to stretching, first sample 1 after pre-stretching, and first sample 1 activated using the disk assemblies. The references for 2, 3 and 4 have identical column references save for the sample number. 
     Activation growth refers to the amount the respective sample grew after activating the film. TD (transverse direction) @ 25%, is a measure of the force required to extend the film 25 percent in the transverse (i.e., cross machine) direction. Likewise, TD Ultim. is a measure of the ultimate force (tensile strength) of the respective sample at the breaking point. TD Elongation % is the percentage the film has stretched at TD Ultimate. TD Ult/TD25 is a ratio of the forces from TD Ultim. and TD @ 25%. The basis weight, in grams/square meter is given for each film. The tear strength (MD Tear) as measured by the ASTMD 1922 method is shown at the bottom of Table 2. 
     The first sample set was activated 350% in the prestretch and disk assembly activation whereas the second sample set was activated 250% in the prestretch and disk assembly activation. 
     As can be seen in Table 2, the tear strength for the fully activated films of the present invention (Columns 1. Act, 2. Act., 3 Act. and 4 Act.) show significantly higher tear strength than prior art films. For example, Samples 1 and 2 Act. each have a tear strength of 68 grams and 54 grams, respectively. In comparison, prior art films show tear strengths of 15 and 18 grams. The present invention films therefore provide significantly higher tear resistance by factors of 4 or greater. 
     This property is especially advantageous for use in elastic waistbands and in products including absorbent products and the like, which are often subjected to tearing during manufacturing and consumer use. The increased tear resistance will prevent further tearing and therefore increase the life of the product. 
     While the present invention has been described primarily in the context of absorbent products and the like, it is recognized that the present invention may also be applied to many other applications and environments. For example, the present invention is particularly well-suited for use with disposable articles using the film of the present invention as a waistband component or side panel component. It will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention, and it is intended to cover the claims appended hereto. All such modifications are within the scope of this invention.