Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. When the thermoplastic polyester is selected to include aliphatic and aromatic polyesters, a spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. When the thermoplastic polyester is selected from aliphatic polyesters, a meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. When the thermoplastic polyester is selected to include aliphatic and aromatic polyesters, a spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. When the thermoplastic polyester is selected from aliphatic polyesters, a meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

Methods and apparatuses for producing a zoned and/or layered substrate are described. A method can include providing a first supply of fibers, providing a second supply of fibers, and providing a headbox. The headbox can include a machine direction, a cross-direction, and a first cross-directional divider that separates a first zone of the headbox from a second zone of the headbox in a cross-directional manner. The method can further include transferring the first supply of fibers and the second supply of fibers to the headbox. The method can also include transferring the first supply of fibers and the second supply of fibers through the headbox to provide the substrate.

Methods and apparatuses for producing a zoned and/or layered substrate are described. A method can include providing a first supply of fibers, providing a second supply of fibers, and providing a headbox. The headbox can include a machine direction, a cross-direction, and a first cross-directional divider that separates a first zone of the headbox from a second zone of the headbox in a cross-directional manner. The method can further include transferring the first supply of fibers and the second supply of fibers to the headbox. The method can also include transferring the first supply of fibers and the second supply of fibers through the headbox to provide the substrate.

The present invention is directed to a new polypropylene composition comprising a propylene homopolymer, to a melt-blown fiber comprising the polypropylene composition, to a melt blown web comprising the melt blown fiber and/or the polypropylene composition, to an article comprising the melt blown fiber and/or the melt blown web as well as to the use of the polypropylene composition for improving the relation between pressure drop and hydrohead of a melt-blown web.

An energy storage cell, including at least one electrode/separator assembly received in a housing. The energy storage cell further includes a covering. The covering is disposed at least in some regions between the electrode/separator assembly and the housing. The covering is made of porous material. The porous material of the covering is open-cell.

An energy storage cell, including at least one electrode/separator assembly received in a housing. The energy storage cell further includes a covering. The covering is disposed at least in some regions between the electrode/separator assembly and the housing. The covering is made of porous material. The porous material of the covering is open-cell.

Methods and apparatuses for producing a zoned and/or layered substrate are described. A substrate can include a first layer including a first zone, a second zone, and an interface between zones. The first zone can include a plurality of fibers. The second zone can include a plurality of fibers and can be offset from the first zone in a cross-direction. The interface can include at least some of the plurality of fibers of the first zone and at least some of the plurality of fibers of the second zone to provide a purity gradient with a transition width less than 3.8 cm as defined by the Purity Gradient Test Method as described herein.

Methods and apparatuses for producing a zoned and/or layered substrate are described. A substrate can include a first layer including a first zone, a second zone, and an interface between zones. The first zone can include a plurality of fibers. The second zone can include a plurality of fibers and can be offset from the first zone in a cross-direction. The interface can include at least some of the plurality of fibers of the first zone and at least some of the plurality of fibers of the second zone to provide a purity gradient with a transition width less than 3.8 cm as defined by the Purity Gradient Test Method as described herein.

A bonded and entangled non-woven structure made of at least 50% staple fibers by weight of the bonded and entangled non-woven structure, and at least a partial bonding of the fibers of the non-woven structure. The at least partial bonding including thermally activated bonds between a first polyolefin material produced with a catalyst including at least one metallocene catalyst and having a melting point in the range 130-170 C. and a second material having a melting point which is at least 10 C. higher than the melting point of the first material, the weight of the first material in the non-woven structure being at least 3% of the weight of the nonwoven structure.