Apparatus and method for manufacturing elastic composite structures for absorbent sanitary products

Abstract

To provide an apparatus and a method of manufacturing an elastic composite structure for eliminating or minimizing use of consumable adhesives to secure elastic threads to facing web layers.SOLUTION: An apparatus for manufacturing an elastic composite structure for an absorbent sanitary product includes an anvil with a weld pattern comprising at least one anchoring region and at least one deactivating region. The anchoring region includes anchoring weld parts that anchor elastic threads in a position relative to facing web layers. The deactivating region includes a break bar constructed to sever the threads. A method of manufacturing the elastic composite structure includes: positioning a tensioned elastic thread between the web layers; fusing the web layers to form an anchored zone that includes anchoring bond parts that fuse the web layers to anchor the tensioned elastic threads therebetween; and cutting the threads to form a deactivated zone between adjacent portions of the anchored zone that is free of tensioned threads.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] (Cross - reference to related applications) This invention claims the benefit of U.S. Provisional Patent Application No. 62 / 623,381, filed on January 29, 2018, and U.S. Provisional Patent Application No. 62 / 666,508, filed on May 3, 2018, the disclosures of which are incorporated herein by reference in their entirety.

[0002] Embodiments of the present invention generally relate to absorbent hygiene products, and more specifically, to improved apparatuses and methods for manufacturing an elastic composite structure for use in absorbent hygiene products that include an elastomeric region and a relatively non - elastomeric region while minimizing or eliminating the use of consumable adhesives such as glue.

Background Art

[0003] Absorbent hygiene products such as disposable diapers typically include an elastic composite structure that includes one or more elastic threads. These elastic composite structures are placed at various locations, including within the waistband, throughout the product including within the leg cuff regions, and all or part of the front or back panels of the product. During a typical manufacturing process of an elastic composite structure, the elastic threads are in a tensioned state, and an adhesive is used to secure the elastic threads between two opposing layers of a non - woven material or web. Thereafter, the tension of the elastic threads is released, and the web material is wrinkled or folded in the region containing the adhered elastic threads. In some applications, it is desirable to provide relatively non - elastomeric regions in the elastic composite structure. To create these different regions, an adhesive is applied to some regions of the web material and omitted in other regions. The elastic threads are cut in the regions without adhesive by a cutting unit such as a rotary knife unit, and the cut ends of the elastic threads are deflected back into the adjacent adhesive regions.

[0004] The use of adhesives to bond elastic threads within elastic composite structures presents numerous drawbacks in both the final product and the manufacturing process, including costs associated with consumables and undesirable tactile properties of the final product (e.g., stiffness). While thermal or ultrasonic welding techniques have been proposed as alternatives for bonding and / or cutting elastic threads within elastic composite structures, known ultrasonic techniques for cutting elastic threads tend to create cuts or slits in the web material, thereby reducing the web tension at the cut portion of the web and creating undesirable holes in the final product. Another problem with cutting elastic threads is that the cut ends of the elastic tend to recede beyond the desired boundary of the elasticized area and land somewhere within the elasticized area. This imperfects the elastic pattern and degrades the aesthetic and functional properties of the final product.

[0005] Therefore, improved apparatus and methods are needed for manufacturing elastic composite structures of absorbent sanitary products that maintain tension in the elastic strands within the product's elastic region and do not cleave the web material in the relatively inelastic region. It would be even more desirable for such apparatus and methods to eliminate or minimize the use of consumable adhesives for fixing the elastic threads to the opposing web layer. [Overview of the project] [Means for solving the problem]

[0006] According to one aspect of the present invention, a joining apparatus is disclosed for manufacturing an elastic composite structure having at least one elastic filament fixed between a pair of opposing web layers. The joining apparatus includes a rotating anvil having a surface having a weld pattern comprising at least one fixed area and at least one deactivating area. The at least one fixed area is between a pair of opposing web layers The material includes a plurality of fixed welds constructed to fuse the web layers together and form a fixed joint that secures at least one elastic thread in place to a pair of opposing web layers. At least one deactivating region includes a break bar constructed to detach at least one elastic thread.

[0007] According to another aspect of the present invention, a method for manufacturing an elastic composite structure includes the steps of arranging tensioned elastic threads between a first web layer and a second web layer, and fusing the first web layer to the second web layer to form a fixed zone having a plurality of separate fixed joints for fixing the tensioned elastic threads between them. The method also includes the step of cutting tensioned elastic threads to form an inert zone of the elastic composite structure without tensioned elastic threads, the inert zone being located between adjacent portions of the fixed zone. The method further includes the step of fusing the first web layer to the second web layer within the inert zone.

[0008] According to another aspect of the present invention, the elastic composite structure includes a tensioned elastic yarn, a first web layer located on a first side of the tensioned elastic yarn, a second web layer located on a second side of the tensioned elastic yarn, and a joint pattern that fuses the first web layer to the second web layer. The joint pattern includes at least one joint pattern and an inert zone including the cut end of a first portion of the tensioned elastic yarn and the cut end of a second portion of the tensioned elastic yarn. The inert zone is free of tensioned elastic yarn. The joint pattern also includes a fixing zone that separates both ends of the inert zone. The fixing zone includes a first plurality of joints in the joint pattern that fix the first portion of the tensioned elastic yarn to the first and second web layers, and a second plurality of joints in the joint pattern that fix the second portion of the tensioned elastic yarn to the second portions of the first and second web layers.

[0009] These and other advantages and features will be more readily apparent from the following detailed description of preferred embodiments of the present invention provided in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0010] The drawings illustrate currently conceivable embodiments for carrying out the present invention.

[0011] In the diagram,

[0012] [Figure 1]This is a schematic perspective view of a portion of a manufacturing line for producing elastic composite material structures.

[0013] [Figure 2] This is a schematic perspective view of a rotary anvil usable in the manufacturing line shown in Figure 1, according to one embodiment of the present invention.

[0014] [Figure 3] This is a schematic cross-sectional view of a joining apparatus according to one embodiment of the present invention, which includes the rotating anvil shown in Figure 2 and can be used in the manufacturing line shown in Figure 1.

[0015] [Figure 4] Figure 3 is a detailed view of a part of the joining apparatus, showing a horn aligned with a fixed weld on a rotating anvil, according to one embodiment of the present invention.

[0016] [Figure 5] Figure 3 is a detailed view of a part of the joining apparatus, showing a horn aligned with a break bar on a rotating anvil, according to one embodiment of the present invention.

[0017] [Figure 6] This is a partial top view of a continuous elastic composite structure manufactured using the rotating anvil shown in Figure 2, according to one embodiment of the present invention.

[0018] [Figure 7] This is a schematic top view showing the spaced-out relationship between a non-tensioned elastic yarn, a pair of fixed joints, a pair of clamping joints, and a laminated joint according to various embodiments of the present invention.

[0019] [Figure 8] This is a schematic perspective view of a rotary anvil usable in the manufacturing line shown in Figure 1, according to another embodiment of the present invention.

[0020] [Figure 9]Top view of a plurality of non-segmented absorbent hygiene products including a continuous elastic composite structure manufactured using the production line of FIG. 1 according to an embodiment of the present invention.

[0021] [Figure 10] Flattened representation of an exemplary anvil pattern that can be used to manufacture the continuous elastic composite structure of FIG. 9 according to an embodiment of the present invention.

[0022] [Figure 10A] Detailed view of a part of the rotary anvil of FIG. 10.

[0023] [Figure 11] Top view of a part of a continuous elastic composite structure manufactured using the rotary anvil of FIG. 10 according to an embodiment of the present invention.

[0024] [Figure 11A] Detailed view of a part of the elastic composite structure of FIG. 11A.

[0025] [[ID=ID=28]] [Figure 12] Flattened representation of an exemplary anvil pattern that can be used to manufacture one of the elastic composite structures of FIG. 9 according to another embodiment of the present invention.

[0026] [Figure 13] Top view of a part of a continuous elastic composite structure manufactured using the rotary anvil of FIG. 12 according to another embodiment of the present invention.

[0027] [Figure 13A] Detailed view of a part of the elastic composite structure of FIG. 13.

[0028] [Figure 14] Flattened representation of an exemplary anvil pattern that can be used to manufacture the continuous elastic composite structure of FIG. 9 according to another embodiment of the present invention.

[0029] [Figure 15] This is a partial top view of a continuous elastic composite structure manufactured using the rotating anvil shown in Figure 14, according to another embodiment of the present invention.

[0030] [Figure 16] A flattened representation of an exemplary anvil pattern usable for manufacturing the continuous elastic composite structure shown in Figure 9, according to yet another embodiment of the present invention.

[0031] [Figure 17] This is a partial top view of a continuous elastic composite structure manufactured using the rotating anvil shown in Figure 16, according to another embodiment of the present invention.

[0032] [Figure 18] This figure shows a technique for manufacturing an elastic composite material structure according to another embodiment of the present invention.

[0033] [Figure 19] This is a flattened representation of an exemplary anvil pattern that can be used to manufacture an elastic composite structure according to the technique of Figure 18, according to one embodiment of the present invention.

[0034] [Figure 20] This is a flattened representation of an exemplary anvil pattern that can be used to manufacture an elastic composite structure according to the technique of Figure 18, according to one embodiment of the present invention.

[0035] [Figure 21] This is a partial top view of an elastic composite structure manufactured using the rotating anvil shown in Figures 19 and 20, according to another embodiment of the present invention.

[0036] [Figure 22] This figure shows a technique for manufacturing an elastic composite material structure according to yet another embodiment of the present invention.

[0037] [Figure 23] This figure shows a technique for manufacturing an elastic composite material structure according to yet another embodiment of the present invention.

[0038] [Figure 24] This is a partial cross-sectional view of a cutting unit that can be used to manufacture an elastic composite structure according to the technology shown in Figure 23, according to one embodiment of the present invention.

[0039] [Figure 25] This figure shows a technique for manufacturing an elastic composite material structure according to yet another embodiment of the present invention.

[0040] [Figure 26] A flattened representation of an exemplary anvil pattern on a first rotating anvil, which may be used to manufacture an elastic composite structure according to the technique of Figure 25, according to one embodiment of the present invention.

[0041] [Figure 27] This is a flattened representation of the outer surface of a cutting unit, which can be used to manufacture an elastic composite structure according to the technique shown in Figure 25, according to one embodiment of the present invention.

[0042] [Figure 28] A flattened representation of an exemplary anvil pattern on a second rotating anvil, which may be used to manufacture an elastic composite structure according to the technique of Figure 25, according to one embodiment of the present invention.

[0043] [Figure 29] This is a partial top view of a continuous elastic composite structure manufactured using the rotary anvil of Figures 26 and 28 and the cutting unit of Figure 27, according to another embodiment of the present invention.

[0044] [Figure 30] This is a schematic cross-sectional view of a bonding device usable in the manufacturing line shown in Figure 1, according to an embodiment of the present invention.

[0045] [Figure 31] This is a top view of a continuous elastic composite structure manufactured using the joining apparatus shown in Figure 30, according to one embodiment of the present invention. [Modes for carrying out the invention]

[0046] Embodiments of the present invention provide a method and apparatus for producing an elastic composite structure comprising one or more activated or elasticized zones fixed or attached in a predetermined position to opposing web layers by one or more tensioned elastic yarns, and one or more inert zones that are inelastic with respect to the elasticized zones. The resulting elastic composite structure can be used in absorbent hygiene products such as diapers, disposable adult pants, or feminine care products. As one non-limiting example, the elastic composite structure described herein may be a waistband for a diaper, in which the inert zone is located in a region where an absorbent core is attached to the waistband.

[0047] Referring here to Figure 1, a portion of an exemplary manufacturing line 10 according to one embodiment of the present invention is shown. As shown, the first web layer 12 is supplied in the machine direction 14. The second web layer 16 is similarly supplied in the machine direction 14. The first web layer 12 and the second web layer 16 are materials that can fuse with each other when applied energy is applied to soften or melt and bond one or both of the webs 12, 16 together without using an intermediate layer of adhesive such as glue. The opposing pair of web layers 12, 16 may be made of the same type of material or different materials, according to alternative embodiments. In non-limiting examples, the first and second web layers 12, 16 may be nonwoven materials, woven materials, films, foams, and / or materials thereof It may include composite or laminated materials.

[0048] One or more elastic yarns 18 are positioned between the first and second web layers 12, 16. Although the following description refers to plural elastic yarns, it should be understood that the methods described herein may be used to produce a single elastic yarn or an elastic composite structure comprising any number of elastic yarns. The elastic yarns 18 are moved in the mechanical direction 14 under tension from a creel assembly (not shown) or a similar apparatus. The elastic yarns 18 may consist of any suitable elastic material, including, in non-limiting examples, a thermoplastic elastomer, natural or synthetic rubber, or a sheet, strand, or ribbon of LYCRA. Each elastic yarn 18 may be supplied in the form of an individual elastomer strand, or it may be a manufactured multifilament product comprising many individual elastomer filaments bonded together by a dry spinning process or the like to form a single fused elastic yarn 18.

[0049] The elastic yarn 18 may have any suitable cross-sectional shape that facilitates the formation of an elastic composite structure having the desired elasticity, visual aesthetics, and manufacturability. In non-limiting examples, the elastic yarn 18 may have a circular, rectangular, square, or irregular cross-sectional shape, as is the case when each elastic yarn 18 is a multifilament product.

[0050] Although the first web layer 12 and the second web layer 16 are shown in Figure 1 and described herein as physically separate components, alternative embodiments may utilize a folded single web structure to trap the elastic yarn 18 between the upper and lower layers of the single web structure. In such embodiments, the portion of the single structure located below the elastic yarn 18 is called the first web layer 12, and the portion of the single structure located above the elastic yarn 18 is called the second web layer 16.

[0051] The production line 10 includes one or more supply assemblies 20, such as guide rollers, which are employed to precisely position and (optionally) tension the elastic yarns 18 as they move in the machine direction 14 toward the joining device 22. Immediately above the joining device 22 are one or more assemblies that supply and guide the first and second web layers 12, 16 and the elastic yarns 18 into the joining device 22. In the illustrated embodiment, these supply assemblies include an upper roller 24, a lower roller 26, and a strand guide roller 28 that guides a composite assembly 30, including the first web layer 12, the second web layer 16, and the elastic yarns 18, into the joining device 22. In alternative embodiments, the rollers 24, 26, 28 may be replaced with other known types of supply assemblies and / or with a single roller unit or other known types of supply assemblies.

[0052] The joining device 22 may be any known ultrasonic welding system, including, in alternative embodiments, a rotary ultrasonic welding system or a blade ultrasonic welding system, as non-limiting examples. In the illustrated embodiment, the joining device 22 includes a rotary anvil 32 and ultrasonic fixed blade horns 34, also known as sonotrodes, which cooperate with each other to join (i.e., fuse) the first web layer 12 to the second web layer 16. Alternative embodiments may include a plurality of fixed blade horns or one or more rotary horns. During the joining process, the elastic filament 18 is fixed or secured in place to the first and second web layers 12, 16, as described in detail below.

[0053] The bonding apparatus 22 also includes one or more frames 36 that support and / or house a motor (not shown) for driving an ultrasonic horn 34, a vibration control unit (not shown) for exciting the horn 34 ultrasonically to vibrate the horn 34, and a second motor (not shown) for driving an anvil 32. The horn 34 and anvil 32 hold the first and second web layers 12, 16 while the elastic thread 18 is held in the space between the horn 34 and the anvil 32. To facilitate ultrasonic bonding to each other, the first and second web layers 12, 16 are positioned spaced apart from each other. During the bonding process, the first and second web layers 12, 16 are exposed to ultrasonic radiation from the horn 34, which increases the vibration of particles within the first and second web layers 12, 16. The ultrasonic radiation or energy is concentrated at specific bonding points where frictional heat fuses the first and second web layers 12, 16 to each other without the need for a consumable adhesive. The bonding apparatus 22 is described herein as an ultrasonic bonding assembly for ultrasonically fusing the first web layer 12 to the second web layer 16, but the techniques described herein may extend to any other known welding or bonding techniques for fusing two or more material layers without the use of adhesives, including sonic, thermal, or pressure bonding techniques, and various other forms of welding known in the industry.

[0054] Referring here to Figure 2, an anvil according to one embodiment of the present invention is shown. As shown, the anvil 32 includes an arrangement of separate projections or welds 38 extending outward from the anvil surface 40. These welds 38 are constructed to (A) fuse the first and second web layers 12, 16 together, and (B) hold or fix elastic threads 18 in place relative to the first and second web layers 12, 16 within the fabricated elastic composite structure. As will be described in more detail below, the fixing welds 38 are designed such that elastic threads 18 passing between two adjacent fixing welds 38 on the surface 40 of the anvil 32 are fixed in place relative to the first and second web layers 12, 16 by frictional resistance preventing the elastic threads 18 from sliding between the pair of resulting joints. The positions of the fixing welds 38 define the fixing area 42 of the anvil 32.

[0055] The anvil 32 also includes one or more additional projections, referred to herein as laminated welds 44. Similar to the constraining or fixed welds 38, the laminated welds 44 fuse the first and second web layers 12, 16 together. The laminated welds 44 differ from the fixed welds 38 in that they do not fix the elastic threads 18 in place relative to the first and second web layers 12, 16.

[0056] The anvil 32 also includes one or more edges or break bars 46 extending outward from the anvil surface 40. Each break bar 46 is configured to break the tensioned elastic yarn 18 as it passes between the horn 34 and the anvil 32 without cutting or perforating the first web layer 12 or the second web layer 16. The pressure or clamping force applied to the elastic yarn 18 as it passes between the horn 34 and the break bar 46 imparts a stress to the elastic yarn 18 that breaks it. In a preferred embodiment, the (one or more) break bars 46 are constructed so as not to join the first and second web layers 12, 16 to each other. In an alternative embodiment, the (one or more) break bars 46 form a joint between the first and second web layers 12, 16 having a geometry that reflects the geometry of the working surface of each break bar 46. The fixed weld 38, the (one or more) laminated welds 44, and the (one or more) break bars 46 all define a pattern 48 or weld pattern of projections extending outward from the surface 40 of the anvil 32.

[0057] In the illustrated embodiment, the break bar 46 has a length equal to or substantially equal to the total length 50 of the projection pattern 48. In alternative embodiments, each break bar 46 may be sized to extend only a portion of the anvil total length 50, as will be described in more detail below. Optionally, one or more break bars 46 may include one or more grooves 56 (shown in perspective) recessed within the working surface 58 of the break bar 46. In yet another embodiment, the break bar 46 is constructed of a series of separate but closely spaced projections or clamp welds, so called because the close spacing of two adjacent clamp welds acts as a clamping point that separates the elastic filament 18 passing through the adjacent clamp welds during the joining process. The break bars 46 are linear and oriented parallel to the axis of rotation 60 of the anvil 32, as shown, or oriented at an angle to the axis of rotation 60, or otherwise to achieve the desired result of cutting the elastic filament 18. It may have any alternative geometric configuration determined based on the design specifications.

[0058] The location of the break bar 46 defines an inert region 62 of the anvil 32, which corresponds to an area of ​​inert or broken elastic filaments in the manufactured elastic composite structure, and is hereafter referred to as the inert zone. One or more laminated welds 44 are also located within the inert region 62 of the anvil 32. In the illustrated embodiment, the inert region 62 includes one break bar 46, with laminated welds 44 positioned on both sides of the break bar 46. Alternative embodiments may include multiple break bars 46 within a given inert region 62, with laminated welds 44 positioned on one or both sides of each break bar 46. In yet another embodiment, the laminated welds 44 may be completely omitted from the inert region 62.

[0059] The specific sizes, shapes, and general arrangements of the fixed welds 38, laminated welds 44, and break bars 46, as well as the total number of welds 38, 44 and (one or more) break bars 46 shown in Figure 2, are intended to illustrate a representative and non-limiting example of the overall pattern 48 of projections on the anvil 32. Alternative embodiments may include any number of welds 38, 44 and (one or more) break bars 46 arranged in any number of alternative configurations to achieve a desired joint pattern on the final product. The working surfaces of the fixed welds 38 and laminated welds 44, respectively, may be configured to form joints of similar size and shape, or joints of different size and / or shape, in the alternative embodiments. As a non-limiting example, the land surfaces of the fixed welds 38 and laminated welds 44, respectively, may be circular, rectangular, crescent-shaped, or have irregular shapes that can be selected to form a desired overall pattern on the final product. As described above, the resulting joint pattern will include one or more fixing zones that fix one or more elastic threads 18 in place relative to the first and second web layers 12, 16 under tension, and one or more inert regions or zones where there are no tensioned elastic threads 18. Because there are no tensioned elastic threads 18, these inert zones define relatively elastic regions within the resulting elastic composite structure.

[0060] In a preferred embodiment, the fixed weld 38, the laminated weld 44, and (one or more) break bars 46 are formed on the anvil 32 using a machining process that removes bulk material from the anvil 32 to create a desired raised pattern 48 of projections against the surface 40 of the anvil 32. Alternatively, the fixed weld 38, the laminated weld 44, and / or (one or more) break bars 46 may be provided on one or more inserts that are mechanically coupled to the surface 40 of the anvil 32.

[0061] Referring here to Figure 3, in one non-limiting embodiment, the working surface 64 of the horn 34 has a smooth or substantially smooth surface contour. Alternatively, the working surface 64 may include an arrangement of protrusions that coincide with or align with the pattern of protrusions 48 on the anvil 32 in order to further facilitate the fusing of the first web layer 12 to the second web layer 16 and the fixing of the elastic filaments 18 to the first and second web layers 12, 16 in place.

[0062] During the manufacturing process, the first and second web layers 12, 16 are positioned between the face 40 of the anvil 32 and the working surface 64 of the horn 34, as shown in Figure 3. The elastic thread 18 is positioned taut between the first and second web layers 12, 16. As generally shown in Figure 3 and in more detail in Figure 4, the working surface 64 of the horn 34 is controlled to maintain a nip gap 66 between the working surface 64 of the horn 34 and the land surfaces 68, 70 of the fixed weld 38 and the laminated weld 44, respectively. The size of the nip gap 66 is determined based on parameters of the manufacturing process to facilitate joining between the first and second web layers 12, 16. The joining apparatus 22 may include any known positioning means 67 that apply force to at least one of the horn 34 and the anvil 32 in order to maintain a desired nip gap 66 between the horn 34 and the anvil 32. The positioning means 67 is not limited For example, it may be a pneumatic assembly (not shown) or a mechanical camshaft (not shown).

[0063] In alternative embodiments, the fixed weld 38 may have a flat working surface, flat sides, or some mixture of curved and straight working surfaces and sides. In the embodiment shown in Figure 4, the land surface 68 of the fixed weld 38 has an arcuate or curved surface profile. This curved profile allows the first and second weld layers 12, 16 to slide against the surface 40 of the anvil 32 during the joining process, thus increasing or decreasing the speed at which the composite assembly 30, including the tensioned elastic strand 18 and the first and second web layers 12, 16, advances toward the joining device 22 relative to the rotational speed of the anvil 32. When the composite web / thread assembly 30 advances at a speed faster than the speed of the anvil 32, the resulting joints are spaced apart by a distance longer than the radial distance between adjacent welds 38, 44 on the anvil surface 40. Similarly, by reducing the feed rate of the composite web / thread assembly 30 relative to the anvil 32 speed, joints are spaced shorter than the radial distance between adjacent welds 38, 44 on the anvil surface 40. The speed mismatch or difference between the web speed and the anvil speed can be controlled to accommodate size variations in the final product. As a result, joining elastic composites for one size diaper can be performed with little to no slippage, while joining elastic composites for larger or smaller diapers can be performed with a greater amount of slippage. Since the same anvil 32 can be used to manufacture multiple sizes of elastic composite structures for use in products of different sizes, the production line 10 equipped with the anvil 32 thus provides dynamic sizing without requiring changes to the tool settings of the production line 10.

[0064] Figure 5 is a detailed view of the relationship between the horn 34 and the break bar 46 on the anvil 32. In the illustrated embodiment, the break bar 46 has a straight side surface 72 and a curved working surface 58 so as to generate slip between the anvil 32 and the first and second web layers 12, 16 in a manner similar to that described above with respect to the fixed weld 38. Alternatively, the entire working surface 58 of the break bar 46 may have a continuous arcuate profile similar to that of the fixed weld 38 in Figure 4. In yet another embodiment, the working surface 58 may be flat or planar, the side surface 72 may be curved, or the break bar 46 may be composed of any other geometric profile that achieves the intended function of cutting the elastic filament 18 and optionally fusing the first and second web layers 12, 16.

[0065] As shown in Figure 5, the working surface 64 of the horn 34 is separated from the working surface 58 of the (one or more) break bar 46 by a nip gap 76. In one embodiment, the nip gap 76 is equal to or substantially equal to the nip gap 66 between the working surface 64 of the horn 34 and the land surfaces 68, 70 of the fixed or laminated welds 38, 44. In an alternative embodiment, it is desirable that the (one or more) break bar 46 form a joint between the first and second web layers 12, 16 thanks to the geometry of the (one or more) break bar 46, the size of the nip gap 76, or a combination thereof.

[0066] Figure 6 shows a portion of an elastic composite structure 78 formed using an anvil 32 having the projection pattern 48 shown in Figure 2. The elastic composite structure 78 is shown in a stretched state with the elastic yarns 18 stretched to the point where the first web layer 12 and the second web layer 16 are flat or substantially flat. The elastic yarns 18 are located between the first and second web layers 12, 16 and are oriented along the longitudinal axis 80 of the elastic composite structure 78. The illustrated embodiment includes three (3) elastic yarns 18, but alternative embodiments may include a single elastic yarn 18 or any number of elastic yarns 18, depending on the design specifications of the final product.

[0067] The first and second web layers 12 and 16 are fixed welded to the anvil 32 by a fixed weld 38 (Figure 2). The anvil 32 fuses with the web layers 12 and 16 at fixed joints 82 where they are in contact, and with the laminated welds 44 (Figure 2) on the anvil 32 at laminated joints 84 where they are in contact with the web layers 12 and 16. One or more break bars 46 on the anvil 32 break the elastic threads 18 and repel them toward the nearest fixed joints 82. When the elastic composite structure 78 can be relaxed, the elastic threads 18 attempt to expand or inflate to return to an untensioned or relaxed state. As the elastic threads 18 expand, frictional forces restrain or fix the threads 18 between adjacent fixed joints 82 and the first and second web layers 12 and 16. As a result, an elastic composite structure 78 is obtained that includes one or more elastic or fixed regions or zones 86 corresponding to fixed regions 86 of the anvil 32, and one or more inelastic or inert zones 88 corresponding to deactivating regions 62 of the anvil 32. The length 90 of one or more fixed zones 86 and the length 92 of one or more inactive zones 88 are defined by controlling the rotational speed of the anvil 32 and the anvil geometry with respect to the feed rate of the composite web / yarn assembly 30 during the joining process.

[0068] Referring here to Figure 7 along with Figure 2 as appropriate, in one embodiment, the proximal edges of adjacent fixed welds 38 are spaced apart by a distance 94 shorter than the strand diameter 96 of a given elastic filament 18 in an unstretched state. As used herein, the term "strand diameter" refers to the smallest measurable cross-sectional width of the elastic filament 18 in an unstretched state. In embodiments where the given elastic filament 18 is a monofilament structure, the strand diameter is the smallest diameter or smallest measurable width of the monofilament structure in an unstretched state. In embodiments where the given elastic filament 18 is a multifilament structure, the term "strand diameter" generally refers to the shortest distance between opposing edges of an outer shape defining an irregular cross-sectional area. As shown in Figure 7, adjacent fixed welds 38 on the anvil 32 form a pair of adjacent fixed joints 82 that act to fix or secure the elastic thread 18, since the distance 98 between the proximal edges of adjacent fixed joints 82 is smaller than the strand diameter 96 of the unstretched elastic thread 18.

[0069] In an embodiment in which the break bar 46 is composed of separate clamping welds, adjacent clamping welds form a pair of adjacent clamping joints 100, each having a proximal edge spaced at a distance 102 shorter than the strand diameter 96 and the distance 98 between adjacent fixed joints 82.

[0070] In an embodiment in which the anvil 32 of Figure 2 includes a plurality of adjacent laminated welds 44, the adjacent welds 44 are spaced at a distance 104 to form a pair of adjacent laminated joints 84, having proximal edges that are spaced at either (A) a distance 106 longer than the strand diameter 96 of a single unstretched elastic yarn 18, as shown by the laminated joint 84A in Figure 7, or (B) a distance 108 longer than the sum of the strand diameters 96 of two or more unstretched elastic yarns 18, as shown by the laminated joint 84B.

[0071] Figure 8 shows an anvil 32 according to an alternative embodiment of the present invention. The anvil 32 includes a projection pattern 110 that differs from the projection pattern 48 described with respect to Figure 2 in that it includes a narrower break bar 46 and does not include a laminated weld 44. In such an embodiment, the resulting elastic composite structure includes a fixed zone similar to the fixed zone 86 shown in Figure 6 and an inert zone that includes a joint line formed by the break bar 46 but does not include a laminated joint. In one embodiment, an adhesive may be used to bond the first and second web layers 12, 16 to each other within the inert zone. Alternatively, a laminated joint similar to the laminated joint 84 in Figure 6 may be formed within the inert zone using a second anvil unit located downstream of the anvil 32, as will be described in more detail below.

[0072] In the embodiments described with reference to Figures 2 to 8, the fixed zone 86 and the inert zone 88 are located laterally on the machine as a result of the specific configuration of the (one or more) break bars 46, (one or more) laminated welds 44 (when in use), and the fixed welds 38 on the anvil 32. The resulting elastic composite structure 78 extends over a similar width in the cross-sectional direction 54. Figures 10, 12, 14, and 16 show alternative anvil projection patterns that may be used in the joining apparatus 22 of Figure 1 to form an inert zone 88 that extends over only a portion of the total width of the resulting elastic composite structure. These alternative projection patterns may be used to manufacture continuous elastic composite structures such as the front waist panel 112 and rear waist panel 114 shown in Figure 9. As illustrated, the front and rear waist panels 112, 114 include a fixing zone 86 containing a plurality of fixing joints for securing the elastic yarn 18, and an inert zone 88 defining the mounting positions of the respective absorbent cores 116 of the disposable diaper or pants, and in some embodiments may include lamination joints. The line 118 represents the product cutting line. Each of Figures 10, 12, 14, and 16 should be understood to show one exemplary and non-limiting pattern of projections for manufacturing the waist panels 112, 114. The concepts described herein may also extend to the manufacture of a final product having one or more fixed zones and one or more inert zones using an anvil having an alternative projection pattern different from those described with respect to Figures 10, 12, 14, and 16. Thus, the projection pattern of the anvil may be modified from that shown herein to create an elastic composite structure having one or more fixed zones and one or more inert zones of different size and / or position for the embodiments specifically shown herein.

[0073] Figure 10 is a flattened representation of the outer circumferential surface 40 of the anvil 32 according to an embodiment in which the anvil 32 includes a pattern of protrusions 120 that forms the inert zone 88 and fixed zone 86 of Figure 9. The pattern of protrusions 120 includes a plurality of fixed weld lines 122 spaced apart from each other along the circumferential axis 124 of the anvil surface 40. The fixed weld lines 122 define the fixed region 126 of the pattern of protrusions 120. The pattern of protrusions 120 also includes a break bar 128 and a plurality of layered weld lines 130 that collectively define the inert region 132.

[0074] As shown in the detailed view provided in Figure 10A, each of the fixed weld lines 122 includes a plurality of separate fixed welds 38. Similarly, each of the laminated weld lines 130 includes a plurality of separate laminated welds 44, which are spaced apart from each other at a distance longer than the distance between the fixed welds 38. In alternative embodiments, each laminated weld line 130 may consist of a single laminated weld 44, or the laminated weld lines 130 may be omitted entirely. The break bar 128 may be formed having a continuous working surface as shown, or it may include one or more grooves similar to the groove 56 in Figure 2.

[0075] In the illustrated embodiment, the break bar 128, the laminated weld line 130, and the fixed weld line 122 have similar sinusoidal geometric shapes that form an overall sinusoidal pattern across the anvil surface 40. In this embodiment, the break bar 128 is constructed to fuse the first and second web layers 12, 16 during the joining process and to cut (one or more) elastic threads 18 passing between the break bar 128 and the horn 34 (Figure 1). In an alternative embodiment, one or more of the laminated weld lines 130 that are directly adjacent to the leading and trailing edges of the inactivation region 62 may be omitted. The break bar 128, the laminated weld line 130, and the fixed weld line 122 may be straight, curved, or, in an alternative embodiment, may be arranged separately to create a continuous and repeating overall pattern in the final product.

[0076] As shown in Figure 11, the joining process creates an overall pattern of fixed and laminated joint lines 134 and 136 on the resulting elastic composite structure 138 that reflects the geometry of the fixed weld lines 122 and laminated weld lines 130 in the projection pattern 120 of Figure 10. Thus, in embodiments where the weld lines 122 and 130 are sinusoidal, the resulting joint lines 134 and 136 have a similar sinusoidal pattern. Alternative joining patterns on the elastic composite structure 138 can be achieved by changing the geometry of the corresponding weld lines 122 and 130 on the anvil 32. In the illustrated embodiment, a continuous joint line 140 is formed by a break bar 128. This cuts the elastic thread 18. The cut or severed end 142 of the elastic thread 18 springs back toward the nearest fixed joint line 134, thereby fixing the two segmented portions 18A, 18B of a given cut elastic thread 18 in place relative to the first and second web layers 12, 16 under tension. In an alternative embodiment, the break bar 128 may be configured to cut the elastic thread 18 without fusing the first and second web layers 12, 16. The fixed joint line 134 also joins the first and second web layers 12, 16 to each other and defines a fixed zone 86. The first and second web layers 12, 16 are joined to each other within the inert zone 88 by a continuous joint line 140 formed by the break bar 128 and by a laminated joint line 136 formed by the laminated weld line 130 on the anvil 32. Similar to the embodiments described above, the fixed joint line 134 collectively defines the fixed zone 86 on the elastic composite structure 138. The inert zone 88 defines the laminated joint line 136 and the continuous joint line 140 (if formed).

[0077] Figure 12 shows a pattern of protrusions 144 on the anvil 32 according to an alternative embodiment of the present invention. The pattern of protrusions 144 includes fixed weld lines 122, which are arranged similarly to those included in the pattern of protrusions 120 in Figure 10 and include a separate fixed weld similar to the fixed weld 38 in Figure 10A. The pattern of protrusions 144 also includes a pair of break bars 128, one of which is positioned at the leading edge of the inert region 132 and the other at the trailing edge of the inert region 132. A series of laminated weld lines 130 are positioned between the break bars 128, each including a separate laminated weld similar to the laminated weld 44 in Figure 10A.

[0078] The projection pattern 144 creates an elastic composite structure 138 including the joint pattern shown in Figure 13. Each break bar 128 cuts the elastic filament 18 as it passes over it, so using two break bars 128 creates two cutting points in a given elastic filament 18 passing through the inert region 132 of the anvil 32, resulting in each of these cut elastic filament portions 146 of the elastic filament 18. These cut elastic portions 146 are maintained within the inert zone 88 of the resulting elastic composite structure 138, as shown in Figure 13.

[0079] Figure 14 shows an alternative pattern 148 of protrusions on the anvil 32 according to another embodiment of the present invention. The fixed region 126 includes a fixed weld line 122 similar to that in Figure 10. The deactivation region 132 includes an alternating pattern of fixed weld lines 122 and break bars 128. In one embodiment, the break bars 128 are constructed so as not to fuse the first and second web layers 12, 16. During the joining process, each elastic filament 18 passing through the deactivation region 132 of the anvil 32 is cut by each of the break bars 128. The result is an elastic composite structure 138 shown in Figure 15, which includes a series of cut elastic filament portions 146 corresponding to each elastic filament 18 passing through the deactivation region 132. These cut elastic filament portions 146 are fixed in place by fixed joint lines 134 in the fixed zone 86.

[0080] Another alternative pattern 150 of the protrusion is shown in Figure 16. In this embodiment, as shown in Figure 17, on the resulting elastic composite structure 138, the inactivation region 132 of the pattern 150 includes a continuous weld pattern 152 that simultaneously cuts the elastic filaments 18 to form a corresponding non-destructive joint pattern 154 or geometric design. Each elastic filament 18 passing between the weld pattern 152 and the horn 34 (Figure 1) during the joining process may be cut once or multiple times based on the geometry of the weld pattern 152. In the illustrated embodiment, the weld pattern 152 cuts each of the affected elastic filaments 18 two or more times, resulting in many detached elastic filament portions 146 that are contained within the joint pattern 154 of the elastic composite structure 138. The continuous weld pattern 152 shown in Figure 16 should be understood as just one example of the weld pattern geometry that can be implemented within the pattern 150 of the protrusion. In alternative embodiments, the pattern 150 of the protrusion may be any desired pattern on the resulting elastic composite structure 138. This may include a continuous welding pattern 152 that forms the shape, design, logo, etc.

[0081] The bonding patterns depicted on the elastic composite structure 138 in Figures 11, 13, 15, and 17 were described above as being formed using a single anvil 32 having a pattern of protrusions that define the location and boundaries of fixed and inert zones on the final product. Alternatively, a similar final product may be manufactured using two or more anvils, each containing part of the overall pattern of protrusions. In such embodiments, the multiple anvils are arranged adjacent to each other in the machine transverse direction 54 (i.e., perpendicular to the machine direction 14) and configured to rotate simultaneously around a common axis of rotation.

[0082] In an alternative embodiment, the first and second web layers 12, 16 are fused together using a plurality of bonding devices arranged in series in the mechanical direction 14. Referring to Figure 1, the first bonding device 22 includes a first anvil 32 having a pattern of projections that form a first portion of the overall bonding pattern, and one or more horns 34. The second bonding device 156 is located downstream of the first bonding device 22 in the mechanical direction 14. The second bonding device 156 includes a second horn 158 and a second anvil 160 having a second pattern of projections that complete the overall bonding pattern. In an alternative embodiment, the second bonding device 156 may include a plurality of horns and / or a plurality of anvils.

[0083] Figure 18 shows an exemplary manufacturing method 162 utilizing this two-stage anvil arrangement. Method 162 begins in step 164 by manipulating the first anvil 32 in combination with a horn 34 to join the first and second web layers 12, 16 to each other. The anvil 32 includes one or more break bars 46 for cutting or separating the elastic filaments 18. The resulting intermediate product 166 is shown in Figure 18 with the positions of the horn 34 and (one or more) break bars 46 superimposed on the intermediate product 166 for reference. The intermediate product 166 includes a fixed zone 86 and an inert zone 88, which at this point in the manufacturing process do not include the laminated joint 84. The fixed zone 86 includes a fixed joint line 134 formed by a fixed weld line 122, as described with respect to Figures 11, 13, 15, and 17, and a corresponding fixed weld 38, similar to any of those described with respect to Figures 2, 10, 12, 14, and 16.

[0084] Method 162 continues in step 168 by fusing the first and second web layers 12, 16 within one or more inert zones 88 obtained via a pattern of laminated welds or laminated weld lines similar to those described with respect to Figures 2, 10, 12, 14, and 16. The result is an elastic composite structure 138 having one or more fixed zones 86 and one or more inert zones 88.

[0085] Figures 19 and 20 show flattened representations of the respective outer surfaces of the first anvil 32 and the second anvil 160 according to one embodiment of the present invention. The first anvil 32 includes a first pattern 170 of projections having fixed weld lines 122 and a break bar 128. The second anvil 160 includes a second pattern 172 of projections having a series of laminated weld lines 130. When the anvils 32, 160 are operated in the manner described with respect to method 162 of Figure 18, the first and second patterns of projections 170, 172 form the elastic composite structure 138 shown in Figure 21. In the illustrated embodiment, the break bar 128 shown in Figure 19 is not configured to form a joint between the first and second web layers 12, 16 of the elastic composite structure 138 (Figure 21). In an alternative embodiment, the geometry of the break bar 128 may be designed to form a joint line within an inert zone 88.

[0086] An alternative two-stage joining method 174 is shown in Figure 22. Similar to method 162 in Figure 18, technique 174 is arranged in series in the mechanical direction 14 to form the overall joining pattern. A pair of anvils 32, 160 are utilized. Methods 162, 174 differ from each other in that they use different patterns of protrusions on the anvils 32, 160. During the first step 176 of Method 174, the first anvil 32, which includes a pattern of protrusions forming an intermediate product 178, is used to form the first portion of the overall joining pattern. As shown in Figure 22, the intermediate product 178 includes a separate fixing zone 86 extending across the width of the product 178. The first anvil 32 also includes one or more break bars 46 that cut away the elastic body to create one or more inert zones 88.

[0087] During the second step 180 of Method 174, the overall joint pattern is completed using a first anvil 160 which includes one or more laminated weld lines 130 in addition to fixed weld lines 122. The second anvil 160 forms one or more laminated joints 84 within an inert zone 88 and one or more additional fixed zones 86, resulting in an elastic composite structure 138.

[0088] Another alternative method 182 for forming the elastic composite structure 138 is shown in Figure 23. Method 182 utilizes a production line 10 including a first anvil 32, a cutting unit 184 positioned downstream of the first anvil 32 as shown in Figure 1, and a second anvil 160 positioned downstream of the cutting unit 184. A partial detail view of the cutting unit 184 according to one embodiment of the present invention is provided in Figure 24. The cutting unit 184 includes a rotary knife roll 186 aligned with a rotary anvil 188. A knife 190 is positioned in an insert 192 on the rotary knife roll 186. An anvil insert 194 is inserted into the rotary anvil 188. The cutting unit 184 may include a single knife 190 and a corresponding anvil insert 194, or multiple knife 190 / anvil insert 194 pairs spaced apart from each other around the respective faces of the knife unit 186 and the rotary anvil 188. Each rotating knife roll 186 and the corresponding rotating anvil 188 are spaced apart by a distance that defines a nip gap 196 between the knife 190 and the working surface 198 of the anvil insert 194. In a preferred embodiment, the nip gap 196 is defined such that the force of the knife 190 on the anvil insert 194 is large enough to cut the elastic filament 18 without cutting the first and second web layers 12, 16 or creating slits in them.

[0089] In the illustrated embodiment, the working surface 198 of the anvil insert 194 is inclined between its leading edge 200 and trailing edge 202. The inclined configuration of the working surface 198 allows for adjustment of the size of the nip gap 196 by adjusting the phase or relative rotational position between the knife 190 and the anvil insert 194. In alternative embodiments, the working surface 198 may be flat, curved, or any other arbitrary geometric shape to facilitate the desired cutting function. In another embodiment, the anvil insert 194 may be omitted entirely. The cutting unit 184 is described herein as a crush-cut unit. In another embodiment, the cutting unit 184 may be replaced with an alternative type of cutting unit known in the art, including a unit having a rotating or non-rotating configuration and a laser system.

[0090] Referring again to Figure 23 in combination with Figures 1 to 3 as appropriate, Method 182 begins with step 204, which involves using a first anvil 32 to form a separate fixed joint zone 86 on the intermediate product 206. In one embodiment, the anvil 32 includes a uniform pattern of fixed welds 38 extending around the outer circumferential surface 40 of the anvil 32. During the joining process, the horn 34 vibrates up and down in the direction of arrows 208, 210 (Figure 3) between an up and down position. This vibration can be performed using a mechanical camshaft assembly coupled to the horn 34 or other known position control mechanism 67. When the horn 34 is in its down position, the fixed joint 82 is formed within the desired fixed joint zone 86. When the horn 34 is in its up position, the horn 34 is disconnected from the anvil 32, and a jointless area 212 is formed on the intermediate product. The joint is formed within the product 206. In step 214, the partially joined intermediate product 206 passes through the cutting unit 184, which cuts off one or more of the elastic threads 18 and forms one or more inert zones 88, resulting in the intermediate product 216. In step 218, the intermediate product 216 passes through the second anvil 160, which includes a pattern of protrusions, including fixed weld lines and laminated weld lines, which complete the joint pattern on the elastic composite structure 138.

[0091] Figure 25 shows an alternative method 220 for forming an elastic composite structure 138 using the optional cutting unit 184 and double joining devices 22, 156 arrangement of Figure 1. In this method 220, the joining device 22 comprises at least two horns 34A, 34B and an anvil 32 having a uniform pattern of fixed welds 38 across the outer circumferential surface 40 of the anvil 32. During the first step 222 of method 220, an intermediate product 224 is formed by vibrating the horn 34B between an elevated and a lowered position in the manner described with respect to step 204 (Figure 22) of method 182 to generate a jointless area 226. In step 228, one or more knives 190 cut one or more of the elastic threads 18 to form one or more inert zones 88 in the resulting intermediate product 230. In step 232, a second anvil 160 forms one or more laminated joints within the inert zones 88 to complete the elastic composite structure 138.

[0092] Advantageously, method 220 can be performed to produce different sized final products without tool changes by controlling the time intervals during which the vibrating horn 34B is held in the raised and lowered positions during step 222, and by controlling the web speed relative to the rotational speed of the second anvil 160 during step 232. More specifically, the vibrating horn 34B is held in the raised position for longer time intervals for larger sized products than for smaller sized products to generate a long jointless region 226. During step 232, the relative speed of the web to the anvil is controlled to form a laminated joint pattern extending over the jointless region 226 of a desired amount.

[0093] Figures 26, 27, and 28 are exemplary planar representations of the respective faces of the first anvil 32, knife unit 186 (cutting unit 184 - Figure 1), and second anvil 160, according to another embodiment in which the first anvil 32, knife unit 186, and second anvil 160 are arranged in the series configuration shown in Figure 1 and operated according to a method for producing an elastic composite structure 138 shown in Figure 29. The first anvil 32 includes a first pattern 234 of projections including a fixed weld line 122 that creates a fixed joint line 134 in Figure 29. In the illustrated embodiment, the knife unit 186 includes two knives 190 oriented at a certain angle with respect to the axis of rotation of the knife unit 186. In such a case, the corresponding anvil insert 194 (Figure 24) may be positioned at a similar angle with respect to the axis of rotation of the rotating anvil 188 (Figure 24). The knife 190 of the knife unit 186 cuts the elastic thread 18, forming an inert zone 88 of the elastic composite structure 138. The second anvil 160 (Figure 28) includes a second pattern 236 of projections having a series of laminated weld lines 130 that form a series of laminated joint lines 136 (Figure 29) within the inert zone 88.

[0094] Figure 30 shows a joining device 238 that may be used in place of the joining device 22 in the production line 10 to create an elastic composite structure 240 as shown in Figure 31. In one embodiment, the joining device 238 includes a horn 34 as described above and an anvil 32 including at least one break bar 242 that extends over the length of the pattern of the fixed weld 38 on the anvil 32, similar to the break bar 46 (Figure 2), or extends only over a portion of the entire length, similar to the break bar 128 (Figure 10). The first and second web layers 12, 16 and one or more tensioned elastic yarns 18 are oriented on the surface 40 of the anvil 32 and within the gap 66 between the anvil 32 and the horn 34 by either a common guide roller 244 or a plurality of rollers similar to those shown in Figure 3. As it passes between them, one or more threads 18 are cut. Immediately after the cut, the tensioning device 246 increases the tension on the cut threads 18 so that they are pulled backward (upstream) across the face 40 of the anvil 32 toward the common guide roller 244. The frictional force between the cut elastic threads 18 and the first and second web layers 12, 16 prevents the cut elastic threads 18 from retracting to a position upstream of the guide roller 244. Once the cut threads 18 have retracted via the tensioning device 246 by a distance equal to the desired length 248 of the inert zone 88, the anvil 32 continues to rotate in direction 250, forming a fixed joint 82 that fuses the first and second web layers 12, 16 as the horn 34 engages with the fixed weld 38 on the face 40 of the anvil 32. The inert zone 88 shown in Figure 31 is formed during the period when the tensioning device 246 holds (one or more) cut threads 18 in the retracted position.

[0095] After a predetermined period has elapsed during which one or more cut threads 18 have retracted to the trailing edge of the inert zone 88, the tensioning device 246 adjusts the tension of the one or more cut elastic threads 18 back to its original tensioned state, and resumes the downstream movement of the one or more cut elastic threads 18 toward the horn 34. After the one or more cut ends of the one or more cut elastic threads 18 reach the horn 34, they are efficiently threaded again and subsequently fixed in place relative to the first and second web layers 12, 16 by the fixed joints that are subsequently formed.

[0096] In an alternative embodiment, the horn 34 is replaced by a cutting knife (one or more), for example, the cutting unit 184 in Figure 24, and the horn 252 is positioned downstream of the cutting knife. One or more elastic threads 18 are cut using the cutting knife and then slid backward toward one or more guide rollers 244 by the tensioning device 246 in the same manner as described above. When the cut elastic threads 18 have slid a distance equal to the length of the desired inert zone, the tensioning device 246 adjusts the tension of the cut elastic threads 18 so that the cut elastic threads 18 resume movement across the anvil surface 40 between the first and second web layers 12, 16. The interaction between the horn 252 and the fixed weld 38 creates a fixed joint 82 on the resulting elastic composite structure 240.

[0097] In yet another alternative embodiment, the tensioning device 246 is omitted, and the guide roller 244 is replaced by an eccentric roller tensioner (not shown) that rotates to increase or decrease the tension of the composite web / yarn assembly 30 in accordance with a timing pattern synchronized when one or more elastic threads 18 are broken. More specifically, the eccentric roller tensioner is controlled to decrease the tension of the composite web / yarn assembly 30 when one or more elastic threads 18 are broken, or immediately thereafter. By decreasing the tension of the composite web / yarn assembly 30, friction between the broken elastic threads 18 and the first and second web layers 12, 16 is reduced, thereby allowing the broken elastic threads 18 to spring back towards the eccentric roller tensioner. When one or more of the (cut) elastic threads 18 have slid a distance equal to the length of the desired inert zone, the eccentric roller tranformer is controlled to rotate to increase the tension of the composite web / thread assembly 30, thereby increasing the friction between the (one or more) elastic threads 18 and the first and second web layers 12, 16. The increased friction causes the (one or more) elastic threads 18 to resume movement together with the first and second web layers 12, 16 across the anvil surface 40. An inert zone 88 (Figure 31) is formed on the resulting elastic composite structure 240 during the time interval between when the (one or more) elastic threads 18 are cut and then threaded again.

[0098] The apparatus and methods described herein may be used, in non-limiting examples, to create elastic composite structures for the waist area, sub-waist area, and / or leg cuff area of ​​a one-piece or three-piece diaper, without the use of glue. As a result, the resulting elastic composite material has a softer feel and a more uniform ripple pattern in the machine's transverse direction. The apparatus and methods described herein also provide various means of forming different elastic (i.e., fixed) zones and inelastic (i.e., inert) zones in the resulting elastic composite material without creating cuts or slits in the web layer. Thus, the embodiments of the present invention disclosed herein enable a manufacturing process that produces a final product that is structurally more robust than prior art approaches and is more visually and tactilely pleasing to the end customer.

[0099] Accordingly, according to one embodiment of the present invention, a joining apparatus is disclosed for manufacturing an elastic composite structure having at least one elastic filament fixed between a pair of opposing web layers. The joining apparatus includes a rotating anvil having a surface having a weld pattern comprising at least one fixing region and at least one deactivating region. The at least one fixing region includes a plurality of fixing welds constructed to fuse the pair of opposing web layers together and form a fixing joint that fixes at least one elastic filament in place relative to the pair of opposing web layers. The at least one deactivating region includes a break bar constructed to detach at least one elastic filament.

[0100] According to another embodiment of the present invention, a method for manufacturing an elastic composite structure includes the steps of arranging tensioned elastic threads between a first web layer and a second web layer, and fusing the first web layer to the second web layer to form a fixed zone having a plurality of separate fixed joints for fixing the tensioned elastic threads between them. The method also includes the step of cutting tensioned elastic threads to form an inert zone of the elastic composite structure without tensioned elastic threads, the inert zone being located between adjacent portions of the fixed zone. The method further includes the step of fusing the first web layer to the second web layer within the inert zone.

[0101] According to yet another embodiment of the present invention, the elastic composite structure includes a tensioned elastic yarn, a first web layer located on the first side of the tensioned elastic yarn, a second web layer located on the second side of the tensioned elastic yarn, and a joint pattern that fuses the first web layer to the second web layer. The joint pattern includes at least one joint pattern and an inert zone including the cut end of the first portion of the tensioned elastic yarn and the cut end of the second portion of the tensioned elastic yarn. The inert zone is free of tensioned elastic yarn. The joint pattern also includes a fixing zone that separates both ends of the inert zone. The fixing zone includes a first plurality of joints in the joint pattern that fix the first portion of the tensioned elastic yarn to the first and second web layers, and a second plurality of joints in the joint pattern that fix the second portion of the tensioned elastic yarn to the second portion of the first and second web layers.

[0102] Although the present invention has been described in detail in relation to only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, or equivalent configurations that are appropriate to the spirit and scope of the invention, although these have not been described. In addition, although various embodiments of the invention have been described, it should be understood that aspects of the invention may include only a subset of the embodiments described. Therefore, the invention should not be considered limited by the above description, but only by the appended claims.

Claims

1. A bonding apparatus for manufacturing an elastic composite structure comprising elastic threads fixed between a pair of opposing web layers, It comprises a rotating anvil having a rotation axis and a surface, and rotating around the rotation axis, The bonding device is configured to form a bonding pattern in the direction of the rotation axis when the horn is operated, by positioning the pair of opposing web layers and the elastic thread between the horn and the surface of the rotating anvil. The aforementioned rotating anvil is A first contour portion including a plurality of first fixing welds extending outward from the surface of the rotating anvil, wherein adjacent first fixing welds form a pair of adjacent first fixing joints that fuse a pair of opposing web layers together, and the elastic thread passing between the adjacent first fixing joints is fixed in a predetermined position relative to the pair of opposing web layers, thereby forming a fixing zone in which the elastic thread is fixed between the pair of opposing web layers; The system comprises a first break bar extending outward from the surface of the rotating anvil and configured to sever the elastic threads, thereby forming an inert zone where the elastic threads are destroyed, A bonding device in which, during the operation of forming the bonding pattern with the horn, the first break bar overlaps with the first contour portion of the rotating anvil in the direction of rotation such that the fixed zone and the inert zone are formed simultaneously in the direction of rotation.

2. The joining device according to claim 1, further comprising a second contour portion including a plurality of second fixing welds extending outward from the surface of the rotating anvil, wherein adjacent second fixing welds are configured to form a pair of adjacent second fixing joints that further fuse the pair of opposing web layers together, and the elastic thread passing between the adjacent second fixing joints is fixed in a predetermined position relative to the pair of opposing web layers.

3. The joining device according to claim 2, further comprising a second break bar extending outward from the face of the rotating anvil and configured to cut the elastic thread, wherein the first and second contours of the fixed weld are located between the first and second break bars.

4. The bonding apparatus according to claim 3, wherein the first and second break bars are further configured to form a joint between the pair of opposing web layers.

5. The joining device according to claim 1, further comprising a second contour portion including a plurality of second fixed welds extending outward from the face of the rotating anvil, wherein the plurality of second fixed welds and the first break bar each define a portion of a common contour portion extending outward from the face of the rotating anvil.

6. The joining apparatus according to claim 1, further comprising the horn having an operating surface spaced apart from the operating surface of the first break bar and the land surfaces of the plurality of first fixed welds.

7. The bonding apparatus according to claim 6, wherein the horn comprises an ultrasonic horn.

8. The joining device according to claim 6, further comprising means for vibrating the horn between a lowered position in which the horn is in contact with the rotating anvil to form the first fixed joint and an raised position in which the horn is separated from the rotating anvil by a distance that prevents the formation of the first fixed joint.

9. The joining apparatus according to claim 1, further comprising a tensioning device configured to selectively repel the elastic thread, which has been separated by the first break bar, in a downstream direction relative to the upstream movement of the pair of opposing web layers, and to resume the downstream movement between the pair of opposing web layers after a predetermined period of time.

10. The joining apparatus according to claim 1, further comprising a plurality of laminated welds constructed to form a laminated joint that fuses the pair of opposing web layers without fixing the elastic threads at predetermined positions with respect to the pair of opposing web layers.

11. The bonding apparatus according to claim 1, wherein the first break bar is further constructed to form a joint between the pair of opposing web layers.

12. The joining device according to claim 1, wherein the first contour portion has a sinusoidal shape.

13. The joining device according to claim 1, wherein the first break bar includes at least one groove.

14. The joining device according to claim 1, further comprising a second break bar extending outward from the surface of the rotating anvil and configured to cut the elastic thread, wherein the first contour is located between the first and second break bars.

15. The bonding apparatus according to claim 14, wherein the first and second break bars are further configured to form a joint between the pair of opposing web layers.

Images