Laminate having differential bond strengths and absorbent article made therefrom

#Film/nonwoven laminates are used in a wide variety of applications, including outer covers for personal care absorbent articles, such as diapers, training pants, incontinence products, feminine hygiene products, sanitary napkins, wound dressings, bandages and the like. Film/nonwoven laminates also have been found useful in the health care area in such products as surgical drapes and gowns, clean room apparel, and sterilization wrappers, as well as in roll goods, such as tent material and covers for furniture, automobiles and other vehicles. Particularly in the field of personal care absorbent articles, an emphasis has been placed on development of low cost film/nonwoven laminates that form an effective barrier to passage of bodily exudates (liquids and other waste matter), while exhibiting good aesthetic and tactile properties, such as hand feel and drape. It is desirable for the film/nonwoven laminate to simulate woven cloth in tactile properties, while still providing a barrier to bodily exudates. For specific applications, it is also desirable for the laminate to permit the passage of water vapor or other gases (breathable) while retaining liquids.

#One technique employed in attempting to achieve a satisfactory, low cost film/nonwoven laminate has been to use films of increasingly lesser gauge or thickness. Thinner films typically are lower in cost and due to the reduced gauge, often have increased softness and are quieter during use. Such lower gauge films also can be rendered breathable or microporous more easily. Such thin films can have an effective gauge or thickness of 0.6 mil or less and a basis weight of 25.0 grams per square meter (gsm) or less. Particularly, when such low gauge films are achieved by drawing or stretching, such as in the machine direction, the drawing or stretching orients the molecular structure of the polymer molecules within the film in the direction of stretching, thereby increasing the strength of the film in the machine direction. However, the same machine direction oriented film is weakened in the cross machine direction in terms of tensile strength and tear properties. In order to compensate for structural weaknesses in such unidirectionally stretched films, a support layer (or multiple support layers), such as a fibrous nonwoven web, have been laminated to the film layer to form a laminate having, among other properties, increased strength and durability.

#Laminates of stretch-thinned films and nonwovens have been formed using thermal lamination techniques, in which heat and pressure, as with heated pattern rolls and ultrasonics, have been employed. Thermal lamination of films and nonwovens requires, however, that the polymeric materials used in forming the film and nonwoven be thermally compatible in order to effectively laminate the two materials. Thus, thermal lamination techniques can limit the freedom to select film and/or nonwoven polymers based upon cost, processability and/or performance criteria. In addition, even thermally compatible polymers may require a level of heat and pressure that result in the laminate being undesirably stiff and/or having poor tactile properties.

#The above aspects, and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

#FIG. 1 illustrates a cross-section view of one embodiment for the laminate of the present invention.

#FIG. 2 illustrates a cross-section view of another embodiment for the laminate of the present invention.

#As used herein the term “nonwoven” means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (To convert from osy to gsm, multiply osy by 33.91).

#As used herein “joined or joining” includes configurations where one element is directly or indirectly attached to another element by any means including, but not limited to, adhesives, thermal bonding, ultrasonic bonding, chemical bonding, mechanical bonding, pressure bonding, heat and pressure bonding, hydrogen bonding, fasteners, stitching, or other means known to those skilled in the art. Joined also includes elements that are indirectly joined together. By “indirectly joined” it is meant one element is attached to a second element by one or more intermediate members. For instance, the outer layers in an ordinary plywood laminate are indirectly joined to each other by the laminate's intermediate layers.

#As used herein “liquid impermeable” means a material, as tested by a hydro head, which is capable of supporting about 20 cm of water or greater without substantial leakage therethrough. The test method used for determining the resistance of a material to liquid penetration is Federal Test Methods Standard No. 191A Method 5514: “Water Resistance of Cloth; Low Range” dated Jul. 20, 1978.