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  Elastic laminates and methods of manufacturing sameUSPTO Application #: 20070123124Title: Elastic laminates and methods of manufacturing same Abstract: A method for forming an elastic laminate comprising: bonding a first nonwoven to an elastic film to form a laminate; activating the laminate to form an activated laminate; and bonding a consolidated nonwoven to the elastic film of the activated laminate to form the elastic laminate. (end of abstract) Agent: Joseph A Tessari Tredegar Film Products - Richmond, VA, US Inventors: Jeffrey Alan Middlesworth, Bryan L. Matte USPTO Applicaton #: 20070123124 - Class: 442059000 (USPTO) Related Patent Categories: Fabric (woven, Knitted, Or Nonwoven Textile Or Cloth, Etc.), Coated Or Impregnated Woven, Knit, Or Nonwoven Fabric Which Is Not (a) Associated With Another Preformed Layer Or Fiber Layer Or, (b) With Respect To Woven And Knit, Characterized, Respectively, By A Particular Or Differential Weave Or Knit, Wherein The Coating Or Impregnation Is Neither A Foamed Material Nor A Free Metal Or Alloy Layer The Patent Description & Claims data below is from USPTO Patent Application 20070123124. Brief Patent Description - Full Patent Description - Patent Application Claims
REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Application No. 60/740,036, filed Nov. 28, 2005, which is hereby incorporated by reference. FIELD OF INVENTION [0002] The present invention relates generally to elastic laminates and their methods of manufacture, and, more particularly, to breathable elastic laminates having nonwoven surfaces on both sides. BACKGROUND OF INVENTION [0003] Breathable elastic laminates are used in the manufacture of many goods, including, for example, disposable articles such as diapers, feminine sanitary articles, and bandages. These applications require that the laminate be strong, stretchable, and soft to the touch. Improving one of these features, however, tends to diminish the others. Consequently, previously-introduced laminates tend to represent a compromise among softness, elasticity, and strength. [0004] For example, one prior art laminate comprises an apertured elastic laminate produced by vacuum laminating a carded polypropylene nonwoven to a multilayer coextruded elastic film. The laminate is then activated in the cross direction using intermeshing gears. This construction has the advantage of a soft feel, but is limited to two layers (nonwoven and film) and lacks high peel strength. [0005] Another prior art product comprises an apertured elastic film which is activated in the cross direction (CD) and is ultrasonically bonded on each side to a consolidated nonwoven. Although this laminate tends to be strong, it has a harsher feel than desired, requires substantial ultrasonic energy to bond the layers, and, because it has three layers, it tends to lack the level of stretch obtainable from a laminate with just a single layer of nonwoven. [0006] Therefore, there is a need for a breathable laminate that is soft on either side yet stretchable and strong. The present invention fulfills this need among others. SUMMARY OF INVENTION [0007] The invention relates to an elastic laminate having soft, nonwoven surfaces on both sides, yet is stretchable and strong. Specifically, the elastic laminate comprises an elastic inner layer and two outer nonwoven layers, in which each nonwoven layer is rendered extensible through a different method. That is, one nonwoven layer is activated, while the other is consolidated. [0008] Applicants have discovered unexpectedly that the laminate of the present invention has an exceptional degree of cross direction stretch, offers a pleasant, soft feel, and can be bonded ultrasonically at full line speed to obtain an exceptionally strong interlayer bond. Without being bound to any particular theory, applicants hypothesize that the high level of stretch results from "elasticizing" the two nonwoven layers using two different techniques--i.e., activation and consolidation. This approach synergistically combines the strengths of the two technologies, resulting in a laminate having the high tensile strength and a strong bond characteristic of a consolidated/ultrasonically bonded nonwoven, and the softness and tear resistance characteristic of an activated nonwoven. Furthermore, this approach appears to minimize the observed tendency of one nonwoven layer to constrain the extensibility of the other nonwoven layer in the same laminate. [0009] Accordingly, one aspect of the invention is an elastic laminate having two outer nonwoven layers which are rendered extensible using two different techniques. In a preferred embodiment, the elastic laminate comprises: (1) an elastic layer having a first and second side; (2) an activated nonwoven layer bonded to the elastic layer on the first side; and (3) a consolidated nonwoven layer bonded to the elastic layer on the second side. [0010] Another aspect of the invention is a method for producing the laminate described above. In a preferred embodiment, the method comprises: (1) bonding a first nonwoven to an elastic film to form a laminate; (2) activating the laminate to form an activated laminate; and (3) bonding a consolidated nonwoven to the elastic film of the activated laminate to form the elastic laminate. DESCRIPTION OF DRAWINGS [0011] FIG. 1 shows a schematic view of an elastic laminate of the present invention. [0012] FIG. 2 shows a schematic of a manufacturing line for making the elastic laminate of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0013] The present invention relates to an elastic laminate and a method for making it. Briefly, referring to FIG. 1, the elastic laminate 10 comprises an elastic layer 12 having a first and second side, 14, and 15. Preferably, but not necessarily, the elastic layer has apertures 13 or is otherwise modified to be breathable. On the first side 14 is an activated nonwoven layer 16 bonded to the elastic film material 12. As used herein the terms "activated" or "activation" refer to a method or state in which a laminate comprising an elastic layer and at least one less-elastic layer is stretched to an extension limit beyond the deformation point of the less-elastic layer to allow the elastic layer to elongate to the extension limit essentially unimpeded by the less-elastic layer. Activation is a well-known technique. On the second side 15 is a consolidated nonwoven layer 17 bonded to the elastomer film 12. As used herein, the terms "consolidated" or "consolidation" refer to a method or state in which the fibers or fiber-like elements of the nonwoven are aligned, thereby allowing the nonwoven to elongate in a direction perpendicular to the alignment. Consolidation, like activation, is a well-known technique for imparting extensibility to a nonwoven. [0014] Referring to FIG. 2, the method 100 of preparing the laminate 10 is described in connection with a preferred manufacturing apparatus. The method comprises bonding a first nonwoven 50 to an elastic film 60 to form a laminate 65. The elastic film is optionally breathable. Once the laminate 65 is formed, it is activated to form an activated laminate 75. A consolidated nonwoven 55 is then bonded to the elastic film 50 of the activated laminate 75 to form the elastic laminate 95. The elastic laminate 95, its uses, and the method of preparing it are described in detail below. [0015] Referring back to FIG. 1, the elastic layer 12 provides elasticity to the laminate. The elastic layer comprises at least one elastic material. Suitable elastic materials include any material that is capable of being formed into a thin sheet, rendered breathable and bonded to nonwovens. For example, elastic materials include natural and/or synthetic polymeric materials including isoprenes, butadiene-styrene materials, styrene block copolymers (e.g., styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS), or styrene/ethylene-butadiene/styrene (SEBS)), olefinic elastomers, polyether esters, polyurethanes, etc. In certain preferred embodiments, the elastic materials may comprise high performance elastic material such as Kraton.RTM. elastic resins from Kraton Polymers, LLC, which are elastic block copolymers. [0016] The form of an elastic layer 12 can vary and may include, for example, elastic strands, elastic nonwoven, elastic film, elastic adhesive, elastic tacky polymeric web, elastic scrim, etc. For the sake of simplicity, unless otherwise noted, these different forms are referred to collectively herein as "elastic film." In certain preferred embodiments, a monolayer elastic film is used. It should be understood, however, that the present invention in not limited to a monolayer film and, in certain applications, a film having multiple layers may be used. For example, it may be advantageous to have an elastic core between two skin layers to enhance bonding to the nonwoven layers or to facilitate processability. Suitable skin layers are well known and include, for example, polyethylene which may be more or less elastic than the elastic material. The thickness of the elastic film may vary according to the application, although the individual layers of the films are 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). [0017] Preferably, the elastic film is breathable or is modified to be breathable in conventional ways. Such ways include, for example, aperturing, slitting, or impregnating with granular particles to create microvoids upon stretching of the elastic film. [0018] The first nonwoven layer 16 provides a soft and breathable surface once activated (discussed below) on the first side 14 of the elastic layer. Suitable nonwovens are capable of being activated and are less elastic than the elastic layer 12. Suitable nonwovens include loose fibers and webs prepared using know techniques such as, for example, air laying, spun bond, spun lace, bonded melt blown, thermobond, bonded carded. 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 include, for example, fibrous polyolefins such as polyethylenes and polypropylenes, and natural fibers such as cotton and cellulose. Continue reading... Full patent description for Elastic laminates and methods of manufacturing same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Elastic laminates and methods of manufacturing same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Elastic laminates and methods of manufacturing same or other areas of interest. ### Previous Patent Application: Artist's cradle Next Patent Application: Webbing for a seat belt Industry Class: Fabric (woven, knitted, or nonwoven textile or cloth, etc.) ### FreshPatents.com Support Thank you for viewing the Elastic laminates and methods of manufacturing same patent info. 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