Exxon Chemical Patents, Inc.

Exxon Chemical Company

Glenn Allan Stahl

James John Mcalpin

James J McAlpin

Anthony Nicholas Speca

Galen C Richeson

Novel fibers have been made of reactor grade isotactic poly-alpha-olefin wherein polypropylene is produced by single-site catalysis and has a melt flow rate of greater than zero to about 5,000, MWD in the range of about 1.0 to about 3.5.

Polyolefin fibers and their fabrics

This invention relates to improved polypropylene nonwoven fabrics. The fabrics are made from isotactic polypropylene which has been produced with a catalyst systems comprising at least two metallocenes. These nonwoven fabrics, particularly when prepared using a spunbonding process, exhibit significantly improved strength without significant sacrifice of other favorable properties.

Nonwoven fabrics

Propylene homopolymers and copolymers formed by metallocene catalyst system exhibit generally lower melting behavior than previous propylene polymers. This lower melting behavior will be of use in the fabrication and use of fibers and fabrics that depend upon either lower melting behavior in general or upon a melting point differential between two fabrics or fibers to achieve bonding. Such fibers are, for instance, chenille or tufted cord, core and sheath. Fabrics such as spunbonded and meltblown, when combined in SM or SMS fabrics will show bonding at lower temperatures with fewer pinholes. Such fabrics may also be bonded by adhesives such as hot melt, water based and extruded polyolefins. Combinations of Ziegler-Natta catalyzed and metallocene catalyzed polymers are contemplated.

Fibers and fabrics incorporating lower melting propylene polymers

Novel fibers have been made from reactor grade isotactic poly-alpha-olefin wherein polypropylene is produced by single-site catalysis and has a melt flow rate of greater than zero to about 5,000, MWD in the range of about 1.0 to about 3.5.

A propylene, .alpha.-olefin copolymer, where the .alpha.-olefin has 5 or more carbon atoms made with a metallocene catalyst system provides substantially higher cold flow resistance from when the propylene copolymer is made with an .alpha.-olefin having 4 or less carbon atoms. Other properties such as ultimate tensile strength and impact strength are substantially higher as well. Such polymers can be used to advantage in fibers, fabrics, and oriented films.

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Humble, TX, United States of America

Glenn Allan Stahl