Patent Application
20180126618
The present disclosure relates to polymeric materials, and particularly to polymeric films. More particularly, the present disclosure relates to elastic films formed from polymeric material.
According to the present disclosure, an elastic film is made using a manufacturing process. The manufacturing process comprises the steps of extruding a composition to form a molten web and casting the molten web to form a quenched film.
In illustrative embodiments, the manufacturing process used to form the elastic film further includes stretching the quenched film to form a stretched film, relaxing the stretched film to form a relaxed film, and perforating the relaxed film to form at least one aperture therein. Optionally, the manufacturing process may further include the step of ageing the quenched film to form an aged film.
In illustrative embodiments, the composition extruded to form the molten web comprises an elastomer. The quenched film is formed by casting the molten web against a surface of a chill roll using a vacuum box and/or blowing air (e.g., an air knife and/or an air blanket). The quenched film is stretched in a machine direction in at least a 2:1 draw to form the stretched film.
In illustrative embodiments, an apertured elastic film comprises a polyolefin, a styrene block copolymer, a non-styrene block copolymer, or a combination thereof. The apertured elastic film has a basis weight of less than or equal to about 30 gsm. A notched elongation to break of the apertured elastic film is equal to or greater than a notched elongation to break of a comparative apertured elastic film prepared without the stretching.
In illustrative embodiments, an apertured elastic film comprises an elastomer, at least one slit that extends from a top surface of the film through to a bottom surface of the film. At least one edge of the apertured elastic film is folded, thereby providing at least one tear-resistant edge to the apertured elastic film. The apertured elastic film has a basis weight of less than or equal to about 30 gsm.
In illustrative embodiments, an elastic film comprises an elastomer. At least one edge of the elastic film is folded, thereby providing at least one tear-resistant edge to the elastic film. The elastic film has a basis weight of less than or equal to about 30 gsm.
In illustrative embodiments, a personal hygiene product comprises at least one apertured elastic film and at least one outer non-woven layer. The at least one apertured elastic film is configured to contact skin and/or clothing of a user of the personal hygiene product.
Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.
The detailed description particularly refers to the accompanying figures in which:
In some embodiments, the present disclosure provides a multi-layer apertured elastic film that includes a core layer interposed between one or more outer skin layers adjacent to the core layer. A first embodiment of a multi-layered apertured elastic film 2 in accordance with the present disclosure is shown, for example, in
The core layer 4 may include a thermoplastic polymer (or combination of thermoplastic polymers), whereas the outer skin layers 6 and 8 may have either the same composition as the core layer 4 or a different composition than the core layer 4. By way of example, one or both of the first skin layer 6 and the second skin layer 8 may contain a thermoplastic polymer or combination of thermoplastic polymers. The choice of the thermoplastic polymer or combination of thermoplastic polymers in each of the core layer 4, the first skin layer 6, and the second skin layer 8 shown is
In one example, an apertured elastic film 2 in accordance with the present disclosure is formed via a blown film process. In another example, an apertured elastic film 2 in accordance with the present disclosure is formed via a cast film process. The cast film process involves the extrusion of molten polymers through an extrusion die to form a thin film. The film is pinned to the surface of a chill roll with an air knife, an air blanket, and/or a vacuum box.
In illustrative embodiments, a process for making an apertured elastic film 2 in accordance with the present disclosure includes (a) extruding a composition containing a thermoplastic polymer to form a molten web, (b) casting the molten web against a surface of a chill roll using an air knife, an air blanket, a vacuum box, or a combination thereof to form a quenched film, (c) stretching the quenched film in a machine direction in at least a 2:1 draw to form a stretched film, (d) relaxing the stretched film to form a relaxed film, and (e) perforating the relaxed film to introduce at least one aperture therein. Optionally, the process for making an apertured elastic film 2 in accordance with the present disclosure further includes ageing the quenched film to form an aged film, which has an increased elasticity relative to the quenched film, prior to performing the stretching.
It has been discovered that by pre-stretching the quenched film (e.g., in a machine direction in at least a 2:1 draw), a notched elongation to break of the resultant apertured elastic film will be equal to or greater than a notched elongation to break of a comparative apertured elastic film prepared without the stretching. In other words, with pre-stretching, a notch put into a sample film does not reduce the break elongation of the film nearly as much as the same notch put into a similar un-stretched sample. Moreover, it has further been discovered that by using a vacuum box, blowing air (e.g., an air knife and/or an air blanket), or a vacuum box in combination with blowing air to cast the molten web against a chill roll in accordance with the present disclosure, apertured elastic films 2 exhibiting surprisingly and unexpectedly improved properties as compared to other elastic films may be prepared. As further described below, these properties may include reduced basis weight.
In some embodiments, the thermoplastic polymer-containing compositions may be extruded in a cast-embossed process with an engraved pattern (matte or less than about 2-mil depth). In other embodiments, the compositions may be extruded via a blown co-extrusion process. In illustrative embodiments, as further explained below, the film extrusion is performed using a vacuum box casting process, which circumvents the limitations of draw resonance that may affect embossed films, as well as bubble instability that may affect blown films.
In illustrative embodiments, the molten web is cast against the surface of the chill roll under negative pressure using a vacuum box as shown in simplified schematic form in
When a vacuum box 42 is used, the molten polymer may exit the die 40 and hit the chill roll 38 within a smaller distance than in an embossed process. For example, in some embodiments, the melt curtain is configured to hit the chill roll 38 within a distance of less than about 12 inches, 11 inches, 10 inches, 9 inches, 8 inches, 7 inches, 6 inches, 5 inches, 4 inches, 3, inches, 2 inches, or 1 inch. In illustrative embodiments, the melt curtain is configured to exit the die and hit the roll within a distance of less than about 3 inches and, in some examples, within a distance of about or less than 1 inch. One advantage of reducing the distance between the die 40 and the roll surface 38 as compared to in a nipped quench process is that smaller distances are less susceptible to the phenomenon of neck-in. Neck-in refers to a reduction in width of the molten web that occurs as the web leaves the die. By drawing the film 46 onto a surface of the chill roll 38 over a short distance as shown in
In another example, the molten web is cast against the surface of the chill roll under positive pressure using an air knife or air blanket, as shown in simplified schematic form in
In a further example, the molten web is cast against the surface of the chill roll under a combination of negative pressure from a vacuum box, as shown in
Thermoplastic materials that have elastomeric properties are typically called elastomeric materials. Thermoplastic elastomeric materials are generally defined as materials that exhibit high resilience and low creep as though they were covalently crosslinked at ambient temperatures, yet process like thermoplastic non-elastomers and flow when heated above their softening point. The thermoplastic polymer 4 (or combination of thermoplastic polymers 4) used to make an apertured elastic film 2 in accordance with the present disclosure is not restricted, and may include all manner of thermoplastic polymers capable of being stretched.
In illustrative embodiments, the thermoplastic polymer is a polyolefin, (including but not limited to homopolymers, copolymers, terpolymers, and/or blends thereof), a non-styrene block copolymer, a styrene block copolymer, or a combination thereof.
Representative polyolefins that may be used in accordance with the present disclosure include but are not limited to low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), ultra-low density polyethylene (ULDPE), medium density polyethylene, polypropylene, isotactic polypropylene, polybutylene, ethylene-propylene copolymers, polymers made using a single-site catalyst, ethylene maleic anhydride copolymers (EMAs), ethylene vinyl acetate copolymers (EVAs) such as those available under the trade designation ELVAX from E. I. DuPont de Nemours, Inc. (Wilmington, Del.), polymers made using Zeigler-Natta catalysts, styrene-containing block copolymers, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers such as those available under the trade designation SURLYN 1702 from E.I. DuPont de Nemours, Inc., polymethylmethacrylate, polystyrene, ethylene vinyl alcohol, and/or the like, and combinations thereof.
Methods for manufacturing LDPE are described in The Wiley Encyclopedia of Packaging Technology, pp. 753-754 (Aaron L. Brody et al. eds., 2nd Ed. 1997) and in U.S. Pat. No. 5,399,426, both of which are incorporated by reference herein, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
ULDPE may be produced by a variety of processes, including but not limited to gas phase, solution and slurry polymerization as described in The Wiley Encyclopedia of Packaging Technology, pp. 748-50 (Aaron L. Brody et al. eds., 2nd Ed. 1997), incorporated by reference above, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
ULDPE may be manufactured using a Ziegler-Natta catalyst, although a number of other catalysts may also be used. For example, ULDPE may be manufactured with a metallocene catalyst. Alternatively, ULDPE may be manufactured with a catalyst that is a hybrid of a metallocene catalyst and a Ziegler-Natta catalyst. Methods for manufacturing ULDPE are also described in U.S. Pat. No. 5,399,426, U.S. Pat. No. 4,668,752, U.S. Pat. No. 3,058,963, U.S. Pat. No. 2,905,645, U.S. Pat. No. 2,862,917, and U.S. Pat. No. 2,699,457, each of which is incorporated by reference herein in its entirety, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail. The density of ULDPE is achieved by copolymerizing ethylene with a sufficient amount of one or more monomers. In illustrative embodiments, the monomers are selected from 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and combinations thereof. Methods for manufacturing polypropylene are described in Kirk-Othmer Concise Encyclopedia of Chemical Technology, pp. 1420-1421 (Jacqueline I. Kroschwitz et al. eds., 4th Ed. 1999), which is incorporated herein by reference, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
In illustrative embodiments, a polyolefin for use in accordance with the present disclosure includes polyethylene, polypropylene, or a combination thereof. In one example, the polyethylene includes linear low density polyethylene which, in some embodiments, includes a metallocene polyethylene. In another example, the polyethylene includes a combination of linear low density polyethylene and low density polyethylene. In a further example, the polyolefin consists essentially of only linear low density polyethylene.
Representative non-styrene block copolymers (elastomers or plastomers) suitable for use in accordance with the present disclosure include but are not limited to ethylene copolymers. Representative ethylene copolymers include but are not limited to ethylene vinyl acetates; ethylene octane; ethylene butane; ethylene/propylene copolymer or propylene copolymer elastomers, such as those available under the trade designation VISTAMAXX® available from ExxonMobil (Irving, Tex.); ethylene/propylene/diene terpolymer elastomers; metallocene polyolefins, such as polyethylene, poly (1-hexane), copolymers of ethylene and 1-hexene, and poly(1-octene); thermoplastic elastomeric polyurethanes, such as that available under the trade designation MORTHANE PE44-203 polyurethane from Morton International, Inc. (Chicago, Ill.) and the trade designation ESTANE 58237 polyurethane from Noveon Corporation, Inc. (Cleveland, Ohio); polyvinyl ethers; poly-α-olefin-based thermoplastic elastomeric materials, such as those represented by the formula —(CH2CHR)x where R is an alkyl group containing from about 2 to about 10 carbon atoms; poly-α-olefins based on metallocene catalysis, such as ENGAGE 8200, ethylene/poly-α-olefin copolymer available from Dow Plastics Co. (Midland, Mich.); polybutadienes; polybutylenes; polyisobutylenes such as VISTANEX NM L-80, available from Exxon Chemical Co.; polyether block amides such as PEBAX available from Elf Atochem North America, Inc. (Philadelphia, Pa.); and/or the like; and combinations thereof.
Thermoplastic elastomeric materials, in particular block copolymers, useful in accordance with the present disclosure include but are not limited to linear, radial, star, and tapered block copolymers, such as styrene block copolymers. Representative styrene block copolymers for use in accordance with the present disclosure include but are not limited to KRATON® or KRATON®-based styrene block copolymers available from Kraton Polymers, Inc. (Houston, Tex.), styrene-isoprene block copolymers, styrene-(ethylene-butylene) block copolymers, styrene-(ethylene-propylene) block copolymers, styrene-butadiene block copolymers, and/or the like, and combinations thereof. In some embodiments, thermoplastic elastomeric materials in accordance with the present disclosure include polyether esters such as those available under the trade designation HYTREL G3548 from E.I. DuPont de Nemours, and/or polyether block amides such as those available under the trade designation PEBAX from Elf Atochem.
Additional thermoplastic materials which may be used in accordance with the present disclosure include but are not limited to polyesters including amorphous polyester, polyamides, fluorinated thermoplastics such as polyvinylidene fluoride; halogenated thermoplastics such as chlorinated polyethylene, polyether-block-amides such as those available under the trade designation PEBAX 5533 from Elf-Atochem, and/or the like, and combinations thereof.
A precursor film containing a thermoplastic polymer that is stretched, relaxed, and apertured to form an apertured elastic film 2 in accordance with the present disclosure may be prepared by mixing together the thermoplastic polymer (or a combination of thermoplastic polymers) and any optional components until blended, heating the mixture, and then extruding the mixture to form a molten web. A suitable film-forming process may be used to form a precursor film en route to forming an apertured elastic film. For example, the precursor film may be manufactured by casting or extrusion using blown-film, co-extrusion, or single-layer extrusion techniques and/or the like. In one example, the precursor film may be wound onto a winder roll for subsequent stretching in accordance with the present disclosure (e.g., following optional ageing of the quenched film to allow for elasticity of the film to increase over time). In another example, the precursor film may be manufactured in-line with a film stretching apparatus such as shown in
In addition to containing one or more thermoplastic polymers, the precursor film may also contain other optional components to improve the film properties or processing of the film. Representative optional components include but are not limited to anti-oxidants (e.g., added to prevent polymer degradation and/or to reduce the tendency of the film to discolor over time) and processing aids (e.g., added to facilitate extrusion of the precursor film). In one example, the amount of one or more anti-oxidants in the precursor film is less than about 1% by weight of the film and the amount of one or more processing aids is less than about 5% by weight of the film. Additional optional additives include but are not limited to whitening agents (e.g., titanium dioxide), which may be added to increase the opacity of the film. In one example, the amount of one or more whitening agents is less than about 10% by weight of the film. Further optional components include but are not limited to antiblocking agents (e.g., diatomaceous earth) and slip agents (e.g. erucamide a.k.a. erucylamide), which may be added to allow film rolls to unwind properly and to facilitate secondary processing (e.g., diaper making). In one example, the amount of one or more antiblocking agents and/or one or more slip agents is less than about 5% by weight of the film. Further additional optional additives include but are not limited to scents, deodorizers, pigments other than white, noise reducing agents, and/or the like, and combinations thereof. In one example, the amount of one or more scents, deodorizers, pigments other than white, and/or noise reducing agents is less than about 10% by weight of the film.
The type of stretching used to transform a quenched film into an apertured elastic film 2 in accordance with the present disclosure is not restricted. All manner of stretching processes—and combinations of stretching processes are contemplated for use. In illustrative embodiments, the stretching includes MD stretching. In other examples, the stretching may include one or more of CD IMG stretching, MD IMG stretching, cold draw, and/or the like.
In illustrative embodiments, the type of stretching used to transform a quenched film into an apertured elastic film 2 in accordance with the present disclosure includes MD stretching. In addition, in illustrative embodiments, at least a portion of the MD stretching is performed at ambient temperature (i.e., room temperature). In some embodiments, the stretching in the machine direction is in at least a 3:1 draw and, in other embodiments, in at least a 4:1 draw.
In one example, stretching may be achieved via machine direction (MD) orientation by a process analogous to that shown in simplified schematic form in
In illustrative embodiments, a process for making an apertured elastic film 2 in accordance with the present disclosure may be executed as shown in simplified schematic form in
In the MD stretching station 68, the elastic co-extrusion is stretched in a series of three closely spaced rolls with nips. In illustrative embodiments, the film is stretched 100% (2:1) between the first and second roll and an additional 100% (2:1) between the second and third roll. Thus, the total stretch is 4:1 (2×2).
In the relaxing station 70, the speed of downstream rolls is reduced to allow the web to nearly relax and be wound up. Somewhere within the area of relaxation, the perforation may be implemented via the slitting station 74.
As shown in
In some embodiments, the extruding and the casting are achieved via in-line processing, and one or more of the stretching, the relaxing, and the perforating is achieved via post-processing of the quenched film. In other embodiments, at least the extruding, the casting, and the stretching are achieved via in-line processing. In further embodiments, at least the extruding, the casting, the stretching, and the relaxing are achieved via in-line processing. In additional embodiments, each of the extruding, the casting, the stretching, the relaxing, and the perforating is achieved via in-line processing.
In illustrative embodiments, perforating is performed in a machine direction. Perforation of a relaxed film in accordance with the present disclosure may be achieved by a wide array of physical processes, including but not limited to those described in U.S. Patent Application Publication Nos. 2005/0158513 A1 and 2007/0237924 A1. The entire contents of both of these documents are hereby incorporated herein by reference, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
For elastic films that are to be perforated in a relaxed state and subsequently subjected (e.g., by an end user) to post-stretching ranging from about 2:1 to about 2.5:1, a wide array of perforation techniques may be implemented in accordance with the present disclosure. By way of example, a score cutting assembly with gaps between the cutting teeth may be used, and blades or other perforating surfaces may be mounted side by side for cutting against a hardened steel cutting roll. Alternatively, die cutting may be used to form slits aligned nearly with the machine direction In other embodiments, perforation techniques including but not limited to hot needles, water jets, laser perforation, and/or the like, and combinations thereof may be used.
Prior to stretching, the precursor film may have an initial basis weight of less than about 100 grams per square meter (gsm). In one example, the precursor film has an initial basis weight of less than about 75 gsm. The precursor film may be a monolayer film, in which case the entire precursor film comprises the thermoplastic polymer (or combination of thermoplastic polymers). In another example, the precursor film may be a multilayer film as suggested in
In illustrative embodiments, as noted above, an apertured elastic film 2 prepared in accordance with the present disclosure (e.g., by using a vacuum box and/or air knife to cast a molten web containing a thermoplastic polymer (e.g., an elastomer) against a chill roll) may have reduced basis weight as compared to conventional apertured elastic films.
The basis weight of an apertured elastic film 2 in accordance with the present disclosure may be varied based on a desired end use (e.g., the desired properties and/or applications of the apertured elastic film). In one example, the basis weight ranges from about 5 gsm to about 30 gsm. In another example, the basis weight ranges from about 6 gsm to about 25 gsm. In some examples, the basis weight is less than about 50 gsm and, in illustrative embodiments, less than about 45 gsm, 40 gsm, 35 gsm, 30 gsm, 25 gsm, or 20 gsm. In illustrative embodiments, the basis weight is between about 20 gsm and about 30 gsm. Although basis weights outside this range may also be employed (e.g., basis weights above about 30 gsm), lower basis weights minimize material cost as well as maximize consumer satisfaction (e.g., a thinner film may provide increased comfort to the user of a personal hygiene product that includes the film). The basis weight of an apertured elastic film 2 in accordance with the present disclosure may be one of several different values or fall within one of several different ranges. For example, it is within the scope of the present disclosure to select a basis weight to be one of the following values: about 30 gsm, 29 gsm, 28 gsm, 27 gsm, 26 gsm, 25 gsm, 24 gsm, 23 gsm, 22 gsm, 21 gsm, 20 gsm, 19 gsm, 18 gsm, 17 gsm, 16 gsm, 15 gsm, 14 gsm, 13 gsm, 12 gsm, 11 gsm, 10 gsm, 9 gsm, 8 gsm, 7 gsm, 6 gsm, or 5 gsm.
It is also within the scope of the present disclosure for the basis weight of the apertured elastic film 2 to fall within one of many different ranges. In a first set of ranges, the basis weight of the apertured elastic film 2 is in one of the following ranges: about 5 gsm to 30 gsm, 6 gsm to 30 gsm, 7 gsm to 30 gsm, 8 gsm to 30 gsm, 9 gsm to 30 gsm, 10 gsm to 30 gsm, 11 gsm to 30 gsm, 12 gsm to 30 gsm, 13 gsm to 30 gsm, and 14 gsm to 30 gsm. In a second set of ranges, the basis weight of the apertured elastic film is in one of the following ranges: about 5 gsm to 29 gsm, 5 gsm to 28 gsm, 5 gsm to 27 gsm, 5 gsm to 26 gsm, 5 gsm to 25 gsm, 5 gsm to 24 gsm, 5 gsm to 23 gsm, 5 gsm to 22 gsm, 5 gsm to 21 gsm, 5 gsm to 20 gsm, 5 gsm to 19 gsm, 5 gsm to 18 gsm, 5 gsm to 17 gsm, 5 gsm to 16 gsm, 5 gsm to 15 gsm, 5 gsm to 14 gsm, 5 gsm to 13 gsm, 5 gsm to 12 gsm, 5 gsm to 11 gsm, 5 gsm to 10 gsm, 5 gsm to 9 gsm, 5 gsm to 8 gsm, and 5 gsm to 7 gsm. In a third set of ranges, the basis weight of the apertured elastic film 2 is in one of the following ranges: about 6 gsm to 29 gsm, 7 gsm to 29 gsm, 7 gsm to 28 gsm, 7 gsm to 27 gsm, 7 gsm to 26 gsm, 7 gsm to 25 gsm, 7 gsm to 24 gsm, 7 gsm to 23 gsm, 7 gsm to 22 gsm, 7 gsm to 21 gsm, 7 gsm to 20 gsm, 7 gsm to 19 gsm, 7 gsm to 18 gsm, 7 gsm to 17 gsm, 7 gsm to 16 gsm, 7 gsm to 15 gsm, 7 gsm to 14 gsm, and 7 gsm to 13 gsm.
In illustrative embodiments, an apertured elastic film 2 in accordance with the present disclosure exhibits a notched elongation to break that is equal to or greater than a notched elongation to break of a comparative apertured elastic film prepared without the pre-stretching. The basis weight of an apertured elastic film 2 in accordance with the present disclosure may be varied based on a desired notched elongation to break. In one example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of about 30 gsm and a notched elongation to break of at least about 50%. In another example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of about 30 gsm and a notched elongation to break of at least about 60%. In a further example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of less than about 14 gsm and a notched elongation to break of at least about 70%. In a further example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of less than about 14 gsm and a notched elongation to break of at least about 70%. In a further example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of less than about 14 gsm and a notched elongation to break of at least about 80%. In a further example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of less than about 14 gsm and a notched elongation to break of at least about 90%. In a further example, an apertured elastic film 2 in accordance with the present disclosure has a basis weight of less than about 14 gsm and a notched elongation to break of at least about 100%.
The notched elongation to break of an apertured elastic film 2 in accordance with the present disclosure may be one of several different values or fall within one of several different ranges. For example, for an apertured elastic film having a basis weight of less than or equal to about 30 gsm—in some embodiments, less than or equal to about 25 gsm or 20 gsm—it is within the scope of the present disclosure to select a notched elongation to break to be greater than or equal to one of the following values: about 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 110%, 111%, 112%, 113%, 114%, 115%, 116%, 117%, 118%, 119%, 120%, 121%, 122%, 123%, 124%, or 125%.
It is also within the scope of the present disclosure for the notched elongation to break of the apertured elastic film 2 to fall within one of many different ranges. In a first set of ranges, the notched elongation to break for an apertured elastic film having a basis weight of less than or equal to about 30 gsm—in some embodiments, less than or equal to about 25 gsm or 20 gsm—is in one of the following ranges: about 65% to 150%, 65% to 145%, 65% to 140%, 65% to 135%, 65% to 130%, 65% to 125%, 65% to 120%, 65% to 115%, 65% to 110%, 65% to 105%, 65% to 100%, 65% to 95%, 65% to 90%, 65% to 85%, 65% to 80%, and 65% to 75%. In a second set of ranges, the notched elongation to break for an apertured elastic film 2 having a basis weight of less than or equal to about 30 gsm—in some embodiments, less than or equal to about 25 gsm or 20 gsm—is in one of the following ranges: about 66% to 150%, 67% to 150%, 68% to 150%, 69% to 150%, 70% to 150%, 71% to 150%, 72% to 150%, 73% to 150%, 74% to 150%, 75% to 150%, 76% to 150%, 77% to 150%, 78% to 150%, 79% to 150%, 80% to 150%, 81% to 150%, 82% to 150%, 83% to 150%, 84% to 150%, 85% to 150%, 86% to 150%, 87% to 150%, 88% to 150%, 89% to 150%, 90% to 150%, 91% to 150%, 92% to 150%, 93% to 150%, 94% to 150%, 95% to 150%, 96% to 150%, 97% to 150%, 98% to 150%, 99% to 150%, 100% to 150%, 101% to 150%, 102% to 150%, 103% to 150%, 104% to 150%, 105% to 150%, 106% to 150%, 107% to 150%, 108% to 150%, 109% to 150%, 110% to 150%, 111% to 150%, 112% to 150%, 113% to 150%, 114% to 150%, 115% to 150%, 116% to 150%, 117% to 150%, 118% to 150%, 119% to 150%, 120% to 150%, 121% to 150%, 122% to 150%, 123% to 150%, 124% to 150%, and 125% to 150%. In a third set of ranges, the notched elongation to break for an apertured elastic film 2 having a basis weight of less than or equal to about 30 gsm—in some embodiments, less than or equal to about 25 gsm or 20 gsm—is in one of the following ranges: about 60% to 149%, 65% to 145%, 70% to 140%, 75% to 135%, 80% to 135%, 85% to 125%, 90% to 120%, 95% to 115%, 100% to 110%, and 105% to 109%.
In some embodiments, as shown in
In one example, a multi-layer apertured elastic films in accordance with the present disclosure may be manufactured by feed block co-extrusion. In another example, a multi-layer apertured elastic films in accordance with the present disclosure may be made by blown film (tubular) co-extrusion. Methods for feed block and blown film extrusion are described in The Wiley Encyclopedia of Packaging Technology, pp. 233-238 (Aaron L. Brody et al. eds., 2nd Ed. 1997), which is incorporated herein by reference, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail. Methods for film extrusion are also described in U.S. Pat. No. 6,265,055, the entire contents of which are likewise incorporated by reference herein, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
In some embodiments, as described above, the present disclosure provides apertured elastic films (e.g., mono-layer or multi-layer). In other embodiments, the present disclosure further provides elastic films that are not apertured but which contain a folded edge that provides tear-resistance to the film.
A non-apertured elastic film 76 comprising an elastomer is shown in
The at least one folded edge 78 shown in
In addition, the at least one folded edge 78 may also provide increased retroactive force, whereby the elastic film 76 may be used as a replacement for the synthetic fibers that are conventionally used in the waistbands of incontinence briefs, such as the fibers sold under the tradename LYCRA by Invista (Wichita, Kans.). For example, by replacing the LYCRA strands that form the “belly panel” of the incontinence pants with an elastic film in accordance with the present disclosure, elastic panels with a much flatter appearance may be generated.
The elastic film 76 shown in
In some embodiments, a multi-layer film in accordance with the present disclosure may contain one or a plurality of apertured elastic film layers analogous to the core layer 4 shown in
Multi-layer films of a type described above are not limited to any specific kind of film structure. Other film structures may achieve the same or similar result as the three-layer apertured elastic film layer 2 shown in
In the above-described exemplary film structures, each of the elastic film layers A may include two or more elastic film layers in order to better control other film properties, such as the ability to bond to nonwovens. For example, when there are two apertured elastic film layers in one “A” elastic film layer, and when “C” represents the second elastic film layer, some exemplary film structures are as follows:
Additionally, die technology that allows production of multiple layers in a multiplier fashion may be used. For example, an ABA structure may be multiplied from about 10 to about 1000 times. The resulting 10-time multiplied ABA structure may be expressed as follows:
In some embodiments, as described above, the present disclosure provides apertured elastic films 2 (e.g., mono-layer or multi-layer). In other embodiments, the present disclosure further provides personal hygiene products containing one or more apertured elastic films (e.g., mono-layer or multi-layer) in accordance with the present disclosure.
In illustrative embodiments, as shown in
As shown in
In some embodiments, a multi-layer structure in accordance with the present teachings, such as the apertured elastic film 2 shown in
In illustrative embodiments, the core layer 4 shown in
For some embodiments in which the non-woven material 102 contains polypropylene homopolymer, the first skin layer 104 and/or the second skin layer 106 may contain a blend of about 60% C702-20 and 40% Exceed 3518. In other embodiments, the first skin layer 104 and/or the second skin layer 106 may contain a blend of about 85% 35 MFR polypropylene homopolymer and about 15% of an LDPE, such as Equistar NA334.
For some embodiments in which the non-woven material 102 contains bicomponent polyethylene/polypropylene non-woven material, which is sometimes used for softness, the first skin layer 104 and/or the second skin layer 106 may contain a blend of about 60% C702-20 and about 40% Exceed 3518. In other embodiments, the first skin layer 104 and/or the second skin layer 106 may contain (a) a blend of about 75% Exceed 3518 and about 25% of an LDPE, such as Equistar NA334, or (b) 100% of an HDPE resin.
In illustrative embodiments, a personal hygiene product in accordance with the present disclosure includes at least one inner apertured elastic film 2 prepared by a process as described above and at least one outer non-woven layer. The at least one inner apertured elastic film 2 is configured for contacting skin and/or clothing of a user of the personal hygiene product.
In one example, the at least one inner apertured elastic film is bonded to the at least one outer non-woven layer without an adhesive (e.g., via heat sealing, ultrasonic welding, and/or the like). In some embodiments, each of the at least one inner apertured elastic film 2 and the at least one outer non-woven layer comprises polypropylene and/or polyethylene. In illustrative embodiments, each of the at least one inner apertured elastic film 2 and the at least one outer non-woven layer comprises polypropylene. In illustrative embodiments, the at least one apertured elastic film is bonded to the at least one outer non-woven layer via an ultrasonic bond.
For embodiments in which the apertured elastic film to be ultrasonically bonded to a nonwoven material is a co-extrusion analogous to that shown in
In illustrative embodiments, the personal hygiene product in accordance with the present disclosure is configured as an incontinence brief, a surgical gown, or a feminine hygiene product.
The following numbered clauses include embodiments that are contemplated and non-limiting:
Clause 1. A process for making an apertured elastic film comprising the steps of
extruding a composition comprising a polyolefin, a styrene block copolymer, a non-styrene block copolymer, or a combination thereof to form a molten web.
Clause 2. The process of clause 1, any other suitable clause, or combination of suitable clauses, further comprising casting the molten web against a surface of a chill roll using an air knife, an air blanket, a vacuum box, or a combination thereof to form a quenched film.
Clause 3. The process of clause 2, any other suitable clause, or combination of suitable clauses, further comprising stretching the quenched film in a machine direction in at least a 2:1 draw to form a stretched film.
Clause 4. The process of clause 3, any other suitable clause, or combination of suitable clauses, further comprising relaxing the stretched film to form a relaxed film.
Clause 5. The process of clause 4, any other suitable clause, or combination of suitable clauses, further comprising perforating the relaxed film to introduce at least one aperture therein.
Clause 6. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises polyethylene, polypropylene, or a combination thereof.
Clause 7. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises low density polyethylene, high density polyethylene, linear low density polyethylene, ultra-low density polyethylene, or a combination thereof.
Clause 8. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises linear low density polyethylene.
Clause 9. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises linear low density polyethylene and the linear low density polyethylene comprises a metallocene polyethylene.
Clause 10. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises polypropylene.
Clause 11. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the polyolefin comprises polypropylene impact copolymer.
Clause 12. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the styrene block copolymer comprises styrene-isoprene block copolymer, styrene-(ethylene-butylene) block copolymer, styrene-(ethylene-propylene) block copolymer, styrene-butadiene block copolymer, or a combination thereof
Clause 13. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the molten web is cast against the surface of the chill roll under negative pressure by the vacuum box.
Clause 14. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the molten web is cast against the surface of the chill roll under positive pressure by the air knife.
Clause 15. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein at least the extruding and the casting are achieved via in-line processing.
Clause 16. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the extruding and the casting are achieved via in-line processing, and wherein one or more of the stretching, the relaxing, and the perforating is achieved via post-processing of the quenched film.
Clause 17. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein at least the extruding, the casting, and the stretching are achieved via in-line processing.
Clause 18. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein at least the extruding, the casting, the stretching, and the relaxing are achieved via in-line processing.
Clause 19. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein each of the extruding, the casting, the stretching, the relaxing, and the perforating is achieved via in-line processing.
Clause 20. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the stretching in the machine direction is in at least a 3:1 draw.
Clause 21. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the stretching in the machine direction is in at least a 4:1 draw.
Clause 22. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein at least a portion of the stretching is performed at room temperature.
Clause 23. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the perforating is performed in a machine direction.
Clause 24. The process of clause 5, any other suitable clause, or combination of suitable clauses, further comprising co-extruding one or a plurality of additional compositions substantially contemporaneously with the extruding of the composition.
Clause 25. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the extruding of the composition forms a first film layer, wherein the process further comprises co-extruding at least a second composition to form at least one second film layer and at least a third composition to form at least one third film layer, the second composition and the third composition being identical or different, wherein the first film layer is disposed between the at least one second film layer and the at least one third film layer.
Clause 26. The process of clause 25, any other suitable clause, or combination of suitable clauses, wherein each of the second composition and the third composition comprises a polyolefin, wherein the first film layer is a core layer, and wherein each of the at least one second film layer and the at least one third film layer is an outer skin layer.
Clause 27. The process of clause 25, any other suitable clause, or combination of suitable clauses, wherein each of the second composition and the third composition comprises a polyolefin, and wherein the polyolefin is polyethylene, polypropylene, or a combination thereof.
Clause 28. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 50 gsm.
Clause 29. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 40 gsm.
Clause 30. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 30 gsm.
Clause 31. The process of clause 5, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 20 gsm.
Clause 32. A process for making an apertured elastic film comprising the steps of
extruding a composition comprising an elastomer to form a molten web.
Clause 33. The process of clause 32, any other suitable clause, or combination of suitable clauses, further comprising quenching the molten web to form a quenched film.
Clause 34. The process of clause 33, any other suitable clause, or combination of suitable clauses, further comprising ageing the quenched film to form an aged film.
Clause 35. The process of clause 34, any other suitable clause, or combination of suitable clauses, wherein the aged film has an increased elasticity relative to the quenched film.
Clause 36. The process of clause 35, any other suitable clause, or combination of suitable clauses, further comprising stretching the aged film in a machine direction in at least a 2:1 draw to form a stretched film.
Clause 37. The process of clause 36, any other suitable clause, or combination of suitable clauses, further comprising relaxing the stretched film to form a relaxed film.
Clause 38. The process of clause 37, any other suitable clause, or combination of suitable clauses, further comprising perforating the relaxed film to introduce at least one aperture therein.
Clause 39. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the elastomer comprises a polyolefin, a non-styrene block co-polymer, a styrene block copolymer, or a combination thereof.
Clause 40. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the elastomer comprises an ethylene copolymer, an ethylene/propylene copolymer, a propylene copolymer, an ethylene/propylene/diene terpolymer, a metallocene polyolefin, or a combination thereof.
Clause 41. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the elastomer comprises a polypropylene copolymer.
Clause 42. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the extruding and the quenching are achieved via a first in-line process, and wherein one or more of the stretching, the relaxing, and the perforating is achieved via a second in-line process.
Clause 43. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the stretching in the machine direction is in at least a 3:1 draw.
Clause 44. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the stretching in the machine direction is in at least a 4:1 draw.
Clause 45. The process of clause 38, any other suitable clause, or combination of suitable clauses, wherein the perforating is performed in a machine direction.
Clause 46. An apertured elastic film comprising
a polyolefin, a styrene block copolymer, a non-styrene block copolymer, or a combination thereof.
Clause 47. The apertured elastic film of clause 46, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film is prepared by a process comprising stretching a quenched film in a machine direction in at least a 2:1 draw to form a stretched film, relaxing the stretched film to form a relaxed film, and perforating the relaxed film to introduce at least one aperture therein.
Clause 48. The apertured elastic film of clause 47, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 30 gsm.
Clause 49. The aperture elastic film of clause 48, any other suitable clause, or combination of suitable clauses, wherein a notched elongation to break of the apertured elastic film is equal to or greater than a notched elongation to break of a comparative apertured elastic film prepared without the stretching.
Clause 50. The apertured elastic film of clause 49, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 25 gsm.
Clause 51. The apertured elastic film of clause 49, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 20 gsm.
Clause 52. The apertured elastic film of clause 49, any other suitable clause, or combination of suitable clauses, wherein the film has a multi-layer structure comprising at least one core film layer interposed between at least a first skin layer and at least a second skin layer.
Clause 53. The apertured elastic film of clause 52, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 7.5/85/7.5.
Clause 54. The apertured elastic film of clause 52, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 10/80/10.
Clause 55. The apertured elastic film of clause 52, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 5/90/5.
Clause 56. An apertured elastic film comprising
an elastomer.
Clause 57. The apertured elastic film of clause 56, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film comprises at least one slit that extends from a top surface of the film through to a bottom surface of the film.
Clause 58. The apertured elastic film of clause 57, any other suitable clause, or combination of suitable clauses, wherein at least one edge of the apertured elastic film is folded, thereby providing at least one tear-resistant edge to the apertured elastic film.
Clause 59. The apertured elastic film of clause 58, any other suitable clause, or combination of suitable clauses, wherein the apertured elastic film has a basis weight of less than or equal to about 30 gsm.
Clause 60. The apertured elastic film of clause 59, any other suitable clause, or combination of suitable clauses, wherein the film has a multi-layer structure comprising at least one core film layer interposed between at least a first skin layer and at least a second skin layer.
Clause 61. The apertured elastic film of clause 60, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 7.5/85/7.5.
Clause 62. The apertured elastic film of clause 60, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 10/80/10.
Clause 63. The apertured elastic film of clause 60, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 5/90/5.
Clause 64. The apertured elastic film of clause 59, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 25 gsm.
Clause 65. The apertured elastic film of clause 60, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 20 gsm.
Clause 66. An elastic film comprising
an elastomer,
wherein at least one edge of the elastic film is folded, thereby providing at least one tear-resistant edge to the elastic film.
Clause 67. The elastic film of clause 66, any other suitable clause, or combination of suitable clauses, wherein the elastic film has a basis weight of less than or equal to about 30 gsm.
Clause 68. The elastic film of clause 67, any other suitable clause, or combination of suitable clauses, wherein the film has a multi-layer structure comprising at least one core film layer interposed between at least a first skin layer and at least a second skin layer.
Clause 69. The elastic film of clause 68, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 7.5/85/7.5.
Clause 70. The elastic film of clause 68, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 10/80/10.
Clause 71. The elastic film of clause 68, any other suitable clause, or combination of suitable clauses, wherein the multi-layer structure has a layer ratio of about 5/90/5.
Clause 72. The elastic film of clause 68, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 25 gsm.
Clause 73. The elastic film of clause 68, any other suitable clause, or combination of suitable clauses, wherein the basis weight is less than or equal to about 20 gsm.
Clause 74. A personal hygiene product comprising
at least one apertured elastic film prepared by the process of clause 5, any other suitable clause, or combination of suitable clauses, the at least one apertured elastic film being configured for contacting skin and/or clothing of a user of the personal hygiene product, and
at least one outer non-woven layer.
Clause 75. The personal hygiene product of clause 74, any other suitable clause, or combination of suitable clauses, wherein the at least one apertured elastic film is bonded to the at least one outer non-woven layer without an adhesive.
Clause 76. The personal hygiene product of clause 74, any other suitable clause, or combination of suitable clauses, wherein each of the at least one apertured elastic film and the at least one outer non-woven layer comprises polypropylene.
Clause 77. The personal hygiene product of clause 74, any other suitable clause, or combination of suitable clauses, wherein the product is configured as an incontinence brief.
Clause 78. The personal hygiene product of clause 74, any other suitable clause, or combination of suitable clauses, wherein the product is configured as a feminine hygiene product.
Clause 79. The personal hygiene product of clause 74, any other suitable clause, or combination of suitable clauses, wherein the at least one apertured elastic film is bonded to the at least one outer non-woven layer via an ultrasonic bond.
The following examples and representative procedures illustrate features in accordance with the present disclosure, and are provided solely by way of illustration. They are not intended to limit the scope of the appended claims or their equivalents.
For production of the example films, an extrusion cast line with up to 3 extruders was used. The “A” and “B” extruders are 2½ in diameter, and the “C” extruder is 1¾ in diameter. The extruders feed into a combining feedblock manufactured by Cloeren Corporation of Orange, Tex., which can layer the A, B and C extruder outputs in a variety of configurations. From the feedblock, the molten polymer proceeds into a monolayer cast die (manufactured by Cloeren) that is about 36″ wide. The die has an adjustable gap. For the samples described herein, the adjustable gap was maintained between 10 and 40 mils. The molten polymer drops down to a chill roll. For the samples described herein, the chill roll had an embossed pattern FST-250 which was engraved by Pamarco of Roselle, N.J. as their pattern P-2739. The embossed pattern P-2739 is a square pattern (e.g., with lines nearly aligned with the Machine Direction) with 250 squares per inch and a depth of about 31 microns. The roll itself has an 18″ diameter with internal water cooling. The engrave roll pattern may be replaced with other patterns that are shallow enough not to interfere with a vacuum box quench. One alternative is a 40 Ra pattern (40 micro-inch average roughness) generated by a sand-blasting process on a chrome plated roll.
In this experiment, elastic films were made from the formulation XC3-828-2358.0 shown in Table 1, the formulation XC3-828-2358.1 shown in Table 2, the formulation XC3-828-2358.5 shown in Table 3, and the formulation XC3-828-2358.6 shown in Table 4.
Tensile strength of notched films prepared from the formulation XC3-828-2358.0 shown in Table 1, the formulation XC3-828-2358.1 shown in Table 2, the formulation XC3-828-2358.5 shown in Table 3, and the formulation XC3-828-2358.6 shown in Table 4 were evaluated using the Standard Tensile Test (ASTM D882). A rectangular sample one-inch wide was placed in Tensile tester grips that were two inches apart. A one-eighth-inch notch was made at the midpoint on one side of each of the film samples. In the test, the upper jaw moves at 20 inches per minute and proceeds until the sample breaks.
The tensile test data for films prepared from formulation XC3-828-2358.0 are summarized in Table 5 below.
The tensile test data for films prepared from formulation XC3-828-2358.1 are summarized in Table 6 below.
The tensile test data for films prepared from formulation XC3-828-2358.5 are summarized in Table 7 below.
The tensile test data for films prepared from formulation XC3-828-2358.6 are summarized in Table 8 below.
The physical properties of the resultant films prepared from formulations XC3-828-2358.0, XC3-828-2358.1, XC3-828-2358.5, and XC3-828-2358.6 are shown in Table 9 below. All of the films had a 7.5/85/7.5 A/B/A layering.
Films prepared from the formulations XC3-828-2358.0, XC3-828-2358.1, XC3-828-2358.5, and XC3-828-2358.6 were subjected to machine direction prestretching. The MD 100% hysteresis testing data are summarized in Table 10 below.
The MD 100% Hysteresis testing data for the films prepared from the formulations XC3-828-2358.0, XC3-828-2358.1, XC3-828-2358.5, and XC3-828-2358.6 that were not subjected to machine direction prestretching are summarized in Table 11 below.
This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 62/419,805, filed Nov. 9, 2016, and U.S. Provisional Application Ser. No. 62/455,827, filed Feb. 7, 2017, each of which is expressly incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62419805 | Nov 2016 | US | |
| 62455827 | Feb 2017 | US |
