P&G issued US patent for stretch laminate, method of making and absorbent article

Nevin Barich

ALEXANDRIA, Virginia , December 19, 2013 (Journal of Engineering) – According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventor Mansfield, Todd Leon (Cincinnati, OH), filed on April 9, 2012, was published online on December 10, 2013.

The assignee for this patent, patent number 8603059, is The Procter & Gamble Company (Cincinnati, OH).

Reporters obtained the following quote from the background information supplied by the inventors: "Disposable absorbent articles, such as diapers, are designed to contain bodily exudates, such as urine, to prevent the soiling of the wearer's clothing and/or other items (for example, a bed, a chair, a blanket, etc.). The fit of the article to the wearer's body is important in ensuring that these wastes are contained, instead of leaking out. The fit of the article to the wearer's body may be affected by the size of the diaper waist opening, the size of the openings around the thighs, and the length or 'pitch' of the diaper.

"Disposable absorbent articles are also designed to be cost-effective. That is, the average consumer may have second thoughts about using a product that holds itself out as disposable if the cost per article is too high. Thus, manufacturers generally make such articles for use by individuals with a wide range of body types that may be classified by a broad criterion, such as weight, for example.

"It will be recognized that the need to make products that conform to a wide range of body types competes with the desire for the article to fit snugly to the user to contain wastes and limit leakage.

"One way in which manufacturers attempt to balance the competing interests of proper fit and variation in body type is through the use of expandable materials. One such group of materials is known as stretch laminates. As the name suggests, these materials are actually composites of individual components that are laminated together, through the use of an adhesive, for example. A typical stretch laminate will attempt to combine an inner layer defined by a material having good elastomeric properties, to accommodate varying body types, with outer layer or layers defined by a fabric-like material, to accommodate user expectations for look and feel.

"A complication arises in that the outer layer or layers of these stretch laminates may inhibit the operation of the inner layer having good elasticity. Consequently, stretch laminates often undergo a processing step, known as activation, prior to use in the manufacture of an absorbent article, such as a diaper or pant, for example. During activation, a mechanical deformation is imposed on the laminate so that the composite material will exhibit better elasticity, while providing the desired look and feel.

"Unfortunately, the activation process may have unintended consequences for the materials that comprise the laminate. For example, mechanical damage to the inner, elastomer layer, as manifest by ruptures or holes in the elastomer, may occur during the activation process. These holes may be macroscopic, and may be on the order of several millimeters in size. If an excessive number of holes develop, the laminate material may be perceived by the user as defective, or may not provide the desired stretch properties or performance.

"One solution has been to use larger thicknesses, or gauges, of material for the inner layer. Another alternative has been to use specialty nonwoven products, designed and manufactured to be compatible with the activation (or ring-rolling) process, for the outer layers. Both of these solutions increase the cost of the resultant laminate.

"Thus, it would be desirable to provide new stretch laminates and methods for making stretch laminates. In particular, it would be desirable to provide less expensive laminates produced using less expensive materials."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventor's summary information for this patent: "In one aspect, a stretch laminate comprises a first layer comprising an elastomer film, the first layer having a surface, and a second layer comprising a nonwoven material, the second layer having a basis weight of less than about 25 gsm and a surface that is attached to the surface of the first layer. The elastomer film having an engineering tensile strength, at an engineering strain rate of about 600/s, of at least one of about greater than about 14 MPa for a plain specimen or about greater than about 7 MPa for a notched specimen.

"In another aspect, a method of making a stretch laminate is provided, the method comprising providing an elastomer film, the elastomer film having an engineering tensile strength, at an engineering strain rate of about 600/s, of at least one of about greater than about 14 MPa for a plain specimen or about greater than about 7 MPa for a notched specimen, attaching a nonwoven layer having a basis weight of less than about 25 gsm to the elastomer film to form an assembly, and activating the assembly of the elastomer film and the nonwoven layer.

"In a further aspect, an absorbent article having a waist region and a crotch region is provided, the article comprising a backsheet having a longitudinal axis, a topsheet attached to the backsheet and having a body-facing surface, an absorbent core disposed between the backsheet and the topsheet, and a stretch laminate defining at least one region of the absorbent article. The stretch laminate comprises a first layer comprising an elastomer film, the first layer having a surface, and a second layer comprising a nonwoven material, the second layer having a basis weight of less than about 25 gsm and a surface that is attached to the surface of the first layer. The elastomer film having a strength of an engineering tensile strength, at an engineering strain rate of about 600/s, of at least one of about greater than about 14 MPa for a plain specimen or about greater than about 7 MPa for a notched specimen.

"Additional aspects of the disclosure are defined by the claims of this patent."

For more information, see this patent: Mansfield, Todd Leon. Stretch Laminate, Method of Making, and Absorbent Article. U.S. Patent Number 8603059, filed April 9, 2012, and published online on December 10, 2013. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=97&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4817&f=G&l=50&co1=AND&d=PTXT&s1=20131210.PD.&OS=ISD/20131210&RS=ISD/20131210

Keywords for this news article include: Engineering, The Procter & Gamble Company.

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