An absorbent device such as a disposable diaper typically includes a topsheet, an absorbent core, and a backsheet. The topsheet contacts skin of the user of the device and may transmit fluid exudate toward the absorbent core such that the absorbent core may captivate and store the fluid exudate. The backsheet serves as the outer most layer and provides a liquid barrier against staining or soiling clothing near the device by preventing leakage or the passing through of liquids stored in the core. Typically, the topsheet, absorbent core, and backsheet are attached to, sealed to, adhered to, bonded to, and/or molded to each other.
In most absorbent devices, an elastic ear is also attached to, sealed to, adhered to, bonded to, and/or molded to, for example, the backsheet or topsheet, or both. Such an elastic ear can be stretched and attached to a portion of the backsheet to form the sides and leg openings of the absorbent article, to provide a comfortable fit for different anatomies of various users of the absorbent device, to reduce leakage, and the like. The elastic ear typically includes an elastic laminate with an elastic material and one or more nonwoven materials. Unfortunately, current elastic laminates used for such elastic ears tend to be expensive in both material costs and processing costs. For example, an elastic material currently is applied continuously in a cross-direction (CD) and machine direction (MD) of the elastic laminate, and, as such, a larger amount of elastic material is used thereby increasing cost of the elastic laminates.
To reduce the amount of elastic material, individual strips of elastic materials may be initially cut and subsequently attached to one or more of the nonwoven materials of the elastic laminate. Unfortunately, to currently manufacture elastic laminates with individual strips of elastic materials, additional and/or separate processing is often required, thus adding to the manufacturing cost of this laminate. In addition, the lamination equipment is often specialized requiring such equipment as web guiding devices, hold-down belts, and special adhesive application equipment, thereby increasing processing complexity and cost as well as the time to manufacture (e.g. the number of processes or steps used to manufacture the elastic laminate). Additionally, the handling of such individual elastic strips after manufacture, but before being attached to one or more of the nonwoven webs typically tends to be tedious and problematic.
Another manufacturing difficulty using current techniques or processes may also include adjusting for “growth” where the dimensions of a laminate change dimensions when subjected to processing conditions such as changes in the basis weight of nonwoven materials, activation settings, and the like. Unfortunately, today, dimensional tolerances normally need to be reversed engineered to take into account such growth and to achieve the desired end dimensions of the laminate. Such reverse engineering may also increase processing complexity and the manufacturing cost.
Methods for forming an elastic laminate with an elastic strip may be disclosed. For example, one or more strips of elastic material may be extruded onto a first nonwoven web. During such an extrusion, the elastic material may be directly applied to the first nonwoven web continuously in a machine direction and discontinuously in a cross direction to form the elastic laminate with one or more elastic strips on the first nonwoven web. Additionally, in an embodiment, the elastic material may be applied unevenly or non-uniformly in the cross direction when forming the elastic strips on the first nonwoven web during extrusion such that more elastic material may be on the edges of an elastic strip than in the middle portion of an elastic strip and, thus, an elastic strip may have a non-uniform thickness across its width in the cross-direction. Additionally, the elastic material may be applied in the cross-direction such that the elastic strips may be non-uniformly spaced across the width of the first nonwoven web or material. As described herein, the elastic laminate may reduce material and manufacturing costs as well as improve the manufacturing method or process thereof.
In one embodiment, a second nonwoven web may be bonded to the elastic laminate (e.g. the first nonwoven web with the one or more elastic strips). Additionally, the elastic laminate including the first nonwoven web with the one or more elastic strips with or without the second nonwoven bonded thereto may be activated. After activation, the first nonwoven web with the one or more elastic strips with or without the second nonwoven bonded thereto of the elastic laminate may be the same size (e.g. width) as before activation (e.g. the original sizes such as width). In embodiments, the elastic laminate may be cut into a pattern or a portion of the elastic laminate may be cut into a pattern and/or the portion of the elastic laminate may be assembled in an article such as an absorbent article.
The Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to any limitations that solve any or all disadvantages noted in any part of this disclosure.
A more detailed understanding of the embodiments disclosed herein may be had from the following description, given by way of example in conjunction with the accompanying drawings.
A detailed description of illustrative embodiments will now be described with reference to the various Figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.
Systems, methods, or processes may be disclosed for forming an elastic laminate that may be used as an elastic ear for an absorbent article such as a diaper, an adult incontinence implement, and the like. According to an embodiment, the elastic laminate may include a nonwoven web and at least one elastic strip or lane that may be smaller than the nonwoven web (e.g. the width of the nonwoven web). For example, the elastic strip or lane may be continuous in one direction such as a machine direction, rather than being continuous across the cross-direction and machine-direction of the nonwoven web, to reduce the amount of elastic material used and, thus, the cost of the elastic laminate. To form the elastic laminate, the elastic strip or lane may be extruded directly onto the nonwoven web such that the elastic material associated therewith may not need to be cut into a strip and then separately adhered or attached to the nonwoven web as done in typical or current methods or processes, thus, further reducing the cost of the elastic laminate incurred during processing (e.g. equipment cost and/or processing time). Additionally, such an extrusion of the elastic strip or lane directly on the nonwoven web may further improve the manufacturing of the elastic laminate by eliminating the handling of the elastic strips after being cut and before being attached or adhered to the nonwoven web. This improvement may be particularly important when a large number of elastic strips, for example 4 to 40 or more, may be cut and handled separately prior to attaching to one or more nonwoven webs. The process or method described herein may, thus, be capable of manufacturing elastic laminates of one to three or more meters in width and may reduce manufacturing complexity and cost.
According to an example embodiment, by selecting a draw gap (e.g. a distance from the die to the cast roller), a “neck-in” of the elastic material may be controlled in such a way as to create heavy areas or edges (e.g. a non-uniform thickness across width of the strips) on the strips that may act as “tack-down” zones (e.g. as described herein). These heavy areas on the elastic strips may further be created by other means such as by designing the die with a variation in the gap at the opening of the die lip, and the like. Such zones may help reduce creep in the laminate instead of maintaining its integrity in the stretched state. A laminate may experience creep when the elastic strip delaminates from the nonwoven when the laminate may be stretched for an extended period and, the elastic strip may prematurely recover or retract during use, losing its integrity and causing an absorbent article to lose contact with a user.
The elastic material 14 in a molten or semi-molten state may be extruded in elastic strips or lanes directly onto the nonwoven web 12 in contact with the roller 34. For example, as shown in
In an alternate embodiment (not shown), at the extrusion stage 32 (via an extrusion or vacuum lamination process), the elastic material 14 may be extruded from the die 30 onto the roller 34 in one or more strips or lanes and then the nonwoven web or material 12 may be brought in contact with the elastic material 14 such that the elastic material 14 may be between the roller 34 and the nonwoven web or material 12.
Additionally, as described herein, the elastic material 14 in the molten or semi-molten state may be extruded from the die 30 such that the elastic strips or lanes 15 of elastic material 14 may not be applied uniformly spaced in the cross-direction (CD) or may the elastic material 14 may be of different thickness across the width of the elastic strips or lanes 15 in the CD (e.g. to help reduce creep) when extruding the elastic strips or lanes 15 on the nonwoven web 12.
Furthermore, in such an extrusion (e.g. at 32), the elastic material 14 in the molten or semi-molten state may bond with the nonwoven web or material 12 as the elastic material 14 cools (e.g. after the extrusion point 18 where the elastic material 12 may be applied to the nonwoven web or material 12).
Additionally, in embodiments, the elastic material 14 may be extruded onto the nonwoven web 12 into the one or more elastic strips or lanes 15 using other suitable lamination or extrusion techniques (e.g. along with or alternatively to the process shown in
As described above, FIGS. 2 and 3A-3B depict example embodiments of at least a portion of an elastic laminate that includes at least one elastic strip or lane extruded on a nonwoven web at, for example, the extrusion stage 32 of the method or process described in
Additionally, as described above, the elastic material 14 that may be used for the elastic strips 15a, 15b may or may not be uniform across the cross-direction (CD) of the elastic strips 15a, 15b. For example, as described above, more elastic material 14 may be applied when forming the outer edges of the elastic strip 15b than the middle portion of the elastic strip 15b during extrusion to help reduce creep that may arise as described herein. Also, the elastic material 14 may be applied with a uniform thickness across the cross-direction (CD) of the elastic strip 15a.
As shown in FIGS. 2 and 3A-3B, after extruding the elastic strips 15a, 15b on the nonwoven web or material 12, nonwoven portions 13a, 13b, and 13c may be disposed on opposite sides of the elastic strips 15a, 15b. According to an example embodiment, the nonwoven portions 13a, 13b, and 13c may be located along edges 17 and 19 respectively of the elastic laminate 100, may be adjacent to, and may separate or be separated by the elastic strips 15a, 15b.
Additionally, the elastic laminate 100 with the nonwoven portions 13a, 13b, and 13c and elastic strips or lanes 15a, 15b extruded directly thereon, for example, via vacuum lamination as shown in
As shown, in an embodiment, the elastic laminate 100 may enable a simplified manufacturing process or method as described above with respect to
In an example embodiment, the elastic laminate 100 along with the nonwoven web or material 12 and/or 16 described herein may measure about 110 mm to about 190 mm wide in the cross-direction (CD), and in an embodiment may be 150 mm wide in the CD. Additionally, each of the elastic strips or lanes 15a, 15b may measure about 20 mm to about 130 mm wide in the CD, and in example embodiments may be about 35 mm to about 70 mm wide or about 35 mm to about 45 mm wide in the CD. Furthermore, the nonwoven portions 13a, 13b, and 13c, in total, may measure the width of the elastic laminate 100 or the first or second nonwoven web or material 12 or 16 less the width of the elastic strips or lanes 15a, 15b. The width of the nonwoven portions 13a and 13c located along edges 17 and 19 may further match or be equal to the other as shown in FIGS. 2 and 3A-3B.
According to example embodiments, the elastic material 14 and the elastic strips or lanes 15 or 15a, 15b formed therefrom may include a styrene-block copolymer such as styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS), or styrene/ethylene-butadiene/styrene (SEBS), styrene/ethylene-propylene/styrene block copolymers, and the like; blends of different styrene block copolymers; blends of stryrene block copolymers with polyolefins such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and the like; polyolefin based elastomers such as Dow®Infuse™, ExxonMobile® Vistamaxx®, and the like; and/or any combination thereof or any other suitable elastic material. In embodiments, a monolayer elastic strip or lane may be used. It should be understood, however, that an elastic strip or lane having multiple layers may also be used. For example, an elastic core may be provided or used between two skin layers to enhance bonding to the nonwoven layers or to facilitate processability. Suitable skin layers are well known and may include, for example, polyethylene which may be more or less elastic than the elastic material. The thickness of the elastic strip or lane may vary, although the individual layers of the films may be typically thin (e.g., the elastic core is usually, but not necessarily, less than 100 microns, and skin layers, if used, are usually less than 20 microns).
In one embodiment, the elastic material 14 and/or the elastic strips or lanes 15 or 15a, 15b formed therefrom may include a blend of SIS, polyethylene, and polystyrene either as a monolayer or a coextruded with skin layers. Additionally, as described herein, the elastic material 14 and the elastic strips or lanes 15 or 15a, 15b formed therefrom may also be a monolayer film, may be a coextruded film, and the like in embodiments.
Additionally, in embodiments, the nonwoven web or materials 12 and/or 16 may be a fibrous material or web such as staple fiber materials including thermal bonded carded fibers, air through bonded carded fibers, spunlace fibers, spunbond or continuous fibers, and the like that may be made of polyethylene (PE), polypropylene (PP), a bicomponent or blends of PE and PP, or other materials. For example, suitable nonwovens may include loose fibers and webs prepared using know techniques such as, for example, air laying, spunbond, spun lace, bonded melt blown, thermobond, bonded carded. Additionally, the nonwoven material may be homogeneous or contain a variety of woven materials including bi-component fibers (e.g. having an inner core of one material and an outer core of a second material), fibers of different morphologies, geometries, and surface finishes. Suitable nonwovens materials may also include, for example, fibrous polyolefins such as polyethylenes and polypropylenes, and natural fibers such as cotton and cellulose.
According to an example embodiment, the properties and/or materials of the elastic material 14 and/or the nonwoven materials or webs 12 and/or 16 may be selected and/or manipulated to meet one or more benchmarks that may be desired for the elastic laminate, and, thus, the elastic ear that may be formed therefrom. For example, in an embodiment, the properties and/or materials of the elastic material 14 and/or the nonwoven materials or webs 12 and/or 16 may be selected and/or manipulated such that a piece of elastic laminate cut in the shape of 300 in
Referring back to
As described above, in an alternate embodiment (not shown) at the extrusion stage 32 (via an extrusion or vacuum lamination process), the elastic material 14 may be extruded from the die 30 onto the roller 34 in one or more strips or lanes and then the nonwoven web or material 12 may be brought in contact with the elastic material 14 such that the elastic material 14 may be between the roller 34 and the nonwoven web or material 12 to extrude the one or more elastic strips thereon. In such an embodiment, the nonwoven web or material 16 may be bonded to the opposite side of the laminate in the extrusion process 32 such that the nonwoven web or material 16 may be bonded to the surface of the first nonwoven 12 with the one or more elastic strips or lanes 15 or 15a, 15b.
As shown in FIGS. 1A and 1C-1E, after the nonwoven web or material 12 may be extruded with the one or more strips or lanes of elastic material 14 at the extrusion stage 32 and/or may be bonded to the second non-elastic material 16 at the bonding stage 33, the elastic laminate (e.g. 100) that may be formed therefrom may be further stretched or activated at an activation stage 35. As shown in
In an embodiment, the parallel activation rollers 42a, 42b may have circumferentially oriented teeth (e.g. as shown in
For example, for stretching the elastic laminate in the cross-direction, as shown in
As shown in
The dimensions of a laminate may change during processing and manufacturing, such as during an activation stage (e.g., stage 35) and is referred to as “growth”. As such, dimensional tolerances normally need to be reversed engineered from what results from the processing or manufacturing such that the desired end dimensions of the laminate may be achieved. For example, the basis weight of the nonwovens and the setting for activation such as the depth of teeth of the rollers used during activation (e.g. the rollers 42a, 42b such as the activation rollers) to give more or less stretch of the laminate may affect the growth associated with the laminate. However, during processing or manufacturing using the processes or methods in
In an example embodiment, the elastic laminate 100 after activation (e.g. at 35) may be easier to stretch that the elastic laminate 100 prior to activation. For example, the elastic laminate 100 after activation with the activation strips 21a, 21b may have a lower modulus (e.g. may stretch easier and more) than the nonwoven web or material 12, 16 and elastic laminate before activation Additionally, in embodiments, the elastic laminate 100 after activation may have a 5% tensile force on a one inch wide test strip that is 2-10 times greater in the unactivated lanes (between the elastic strips) than in the activated lanes 21a and 21b. Tensile force is tested via ASTM D882 (2 inch draw gap, 20 inches/min, 1 inch wide specimen width).
After activation, the elastic laminate 100 may then be passed on to other manufacturing processes or methods and/or collected onto a film roll for further processing at a subsequent time. For example, the elastic laminate 100 may be cut into various sizes or portions that may be used in an elastic ear that may be included in an absorbent article. As shown in
Additionally, the elastic laminate 100 or the cut portions thereof (e.g. in a pattern 300 and/or pattern 302) may be processed such that the elastic laminate 100 or the cut portions thereof (e.g. in pattern 300 and/or pattern 302) may be assembled into an absorbent article.
Additionally, an elastic ear 208a and/or 208b may also be attached to, sealed to, adhered to, bonded to, and/or molded to, for example, the backsheet 206, the topsheet, or both. The elastic ear 208a and/or 208b may be stretched to form the sides and leg openings of the absorbent article, to provide a comfortable fit for different anatomies of various users of the absorbent article 200, to reduce leakage, and the like. The elastic ear 208a and/or 208b may further include a fastener (not shown) to keep the absorbent article 200 secured to the user thereof. In an example embodiment, the elastic ear 208a and/or 208b may include the cut portion of the elastic laminate 100 described herein.
Although systems, methods, processes, and/or embodiments may be described herein with respect to various materials, techniques, equipment, such systems, methods, processes, and/or embodiments may be applicable to other applications and environments and may include additional materials, equipment and manufacturing techniques, methods, and/or processes in different orders than those disclosed herein.
This application claims the benefit of U.S. Provisional Application No. 61/699,242, filed Sep. 10, 2012, the disclosures of which are incorporated herein by references in their entirety.
Number | Date | Country | |
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61699242 | Sep 2012 | US |