Nonwoven fabrics comprising polylactic acid having improved strength and toughness
Inventors
Novarino, Elena • Drews, Gary • Hamilton, Jason • Chester, Stephen • Izzo, Alfredo • Newkirk, David D.
Assignees
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Publication Number
US-11674248-B2
Publication Date
2023-06-13
Expiration Date
Abstract
Nonwoven fabrics having a plurality of fibers that are bonded to each other to form a coherent web, wherein the fibers comprise a blend of a polylactic acid (PLA) and at least one secondary alkane sulfonate are provided. The nonwoven fabrics exhibit increased tensile strengths, elongation and toughness.
Core Innovation
A nonwoven fabric is described in which a plurality of fibers are bonded to each other to form a coherent web, where the fibers include a hydrophobic polymeric blend of a biobased aliphatic polyester and at least one secondary alkane sulfonate. The secondary alkane sulfonate has an alkane chain of C10–C18 and includes a sulfonate moiety on secondary carbons of the alkane chain, and it may be present as sodium or potassium salts.
The invention further describes embodiments in which the hydrophobic polymeric blend and the secondary alkane sulfonate are localized relative to the fiber, including in the surface of the fibers or in a sheath of sheath/core bicomponent fibers. In sheath/core bicomponent arrangements, the blend and the secondary alkane sulfonate are located in the sheath region, with specific weight percent ranges defined for the secondary alkane sulfonate relative to the sheath weight.
The document also describes a PLA spunbond nonwoven fabric in which continuous filaments comprise a hydrophobic polymeric blend of PLA and at least one secondary alkane sulfonate, and the web is formed and bonded by calender bonding or air-through bonding. The process integrates blending under heat and pressure to form a molten or semi-molten stream, forming continuous filaments, depositing onto a collection surface, and bonding to form the specified PLA spunbond nonwoven.
Claims Coverage
The document contains two independent claims: one directed to a nonwoven fabric composition and one directed to a process for preparing a PLA spunbond nonwoven fabric. The claim set presents multiple inventive features concentrated on the inclusion of a secondary alkane sulfonate in a hydrophobic polymeric blend, including chemical structure and placement/localization of the sulfonate, and on process integration for forming and bonding PLA continuous filaments into the specified fabric.
Hydrophobic polymeric blend of biobased aliphatic polyester and secondary alkane sulfonate
A nonwoven fabric has a plurality of bonded fibers forming a coherent web, wherein the fibers comprise a hydrophobic polymeric blend of a biobased aliphatic polyester and at least one secondary alkane sulfonate.
Secondary alkane sulfonate with C10–C18 secondary carbon sulfonate structure
At least one secondary alkane sulfonate includes an alkane chain of C10–C18, where at least one secondary carbon of the alkane chain bears a sulfonate moiety.
Sheath/core localization of PLA and secondary alkane sulfonate in sheath
A process for preparing a PLA spunbond nonwoven includes bonding into a PLA spunbond nonwoven in which the continuous filaments comprise a hydrophobic polymeric blend of PLA and the at least one secondary alkane sulfonate, including embodiments where the sheath includes a blend of PLA and the at least one secondary alkane sulfonate.
Calender bonding or air-through bonding of the plurality of fibers
The plurality of fibers are bonded using calender bonding or air-through bonding.
Across the independent claim coverage, the inventive concepts are anchored in forming a coherent bonded nonwoven web from fibers that include a hydrophobic polymeric blend of a biobased aliphatic polyester or PLA with at least one secondary alkane sulfonate having the defined secondary-carbon alkane-sulfonate structure, including specified localization in the fibers or sheath region. The process claim integrates formation of continuous filaments, deposition onto a collection surface, and bonding to form the specified PLA spunbond nonwoven.
Stated Advantages
Increased tensile strength versus an identical fabric lacking at least one secondary alkane sulfonate.
Increased elongation versus an identical fabric lacking at least one secondary alkane sulfonate.
Higher toughness indices including an Index/Relative Index of Toughness and a root mean square Toughness Index per basis weight.
Improved polymer melting and flow at bond points when SAS is included, as described using SEM comparisons.
Improved processing to manage static for high-speed 100% PLA preparation using ionization sources positioned near spinning/collection/calender.
Documented Applications
Composite laminates including SM, SMS, and SMMS.
Absorbent articles including diapers and feminine sanitary pads, with hydrophobic/hydrophilic liquid transport behavior measured via runoff and strike-through tests after multiple insults.
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