Composite Nonwoven Sheet for Absorbent Articles

The patent uses a composite nonwoven fabric structure combining polyester fibers (providing strength) and elastomer fibers (providing stretchability). This composite approach allows achieving both high tensile strength and adequate elongation without increasing basis weight, as the synergistic combination of different fiber types provides multiple functions simultaneously.

The patent creates local dense regions and local non-dense regions within the nonwoven fabric. The dense regions provide strength and structural stability, while the non-dense regions provide flexibility and stretchability. This local differentiation allows the fabric to achieve both high tensile strength and good elongation properties without requiring uniform high basis weight throughout.

By combining polyester fibers (high strength, low elongation) with elastomer fibers (high elongation, flexible), the patent creates a composite structure that maintains high strength-to-weight ratio. This allows using lower basis weight while preventing breakage, as the elastomer components provide flexibility and energy absorption without requiring additional material quantity.

The patent creates a heterogeneous structure with dense regions providing strength anchors and non-dense regions providing flexibility. This local quality differentiation allows the fabric to resist breakage through its dense regions while maintaining overall low basis weight through the non-dense regions, preventing uniform material thickening.

The patent extracts the stretchability function from polyurethane elastomer alone and assigns it to elastomer fibers (which can be polyurethane but also other types). Meanwhile, the structural integrity function is assigned to polyester fibers. This separation allows achieving elongation without necessarily using sticky polyurethane, as other non-sticky elastomer materials can fulfill the stretchability requirement.

By creating a composite of polyester and elastomer fibers, the patent separates the functions: polyester provides structural stability and prevents stickiness, while elastomer provides elongation. This composite approach allows using elastomer materials that do not exhibit sticky texture, as the polyester matrix contains and stabilizes the elastomer components.

The patent incorporates elastomer fibers into the nonwoven fabric structure before any stretch processing is performed. These pre-incorporated elastomer fibers act as built-in stretch elements that can extend without causing fiber breakage or structure breakdown, allowing subsequent stretch processing to be performed safely while maintaining strength.

The composite structure of polyester and elastomer fibers allows the elastomer components to bear the stretch load during processing, protecting the polyester fibers from breakage. The polyester fibers maintain the structural framework while elastomer fibers provide the stretch mechanism, enabling stretch processing without strength loss.