The present invention generally relates to the design and manufacture of nanofiber layers, webs, films, or membranes that may be self-supporting and can function as standalone products. More particularly, the present invention relates to a microporous nanofiber films and the use of such films in a wide variety of products and applications, including applications where physical property tuning is typically limited. Generally, the microporous films of the present invention can function as a standalone nanofiber membrane or can be bonded to other microporous films to produce a layered stacked film stack with customizable properties. Unlike conventional microporous films available in today's market, the microporous films of the present invention can be lighter, require less raw material cost to produce, and can improve operating performances in a variety of applications.

The present invention generally relates to the design and manufacture of nanofiber layers, webs, films, or membranes that may be self-supporting and can function as standalone products. More particularly, the present invention relates to a microporous nanofiber films and the use of such films in a wide variety of products and applications, including applications where physical property tuning is typically limited. Generally, the microporous films of the present invention can function as a standalone nanofiber membrane or can be bonded to other microporous films to produce a layered stacked film stack with customizable properties. Unlike conventional microporous films available in today's market, the microporous films of the present invention can be lighter, require less raw material cost to produce, and can improve operating performances in a variety of applications.

A multi-laminar electrospun nanofiber scaffold for use in repairing a defect in a tissue substrate is provided. The scaffold includes a first layer formed by a first plurality of electrospun polymeric fibers, and a second layer formed by a second plurality of electrospun polymeric fibers. The second layer is combined with the first layer. A first portion of the scaffold includes a higher density of fibers than a second portion of the scaffold, and the first portion has a higher tensile strength than the second portion. The scaffold is configured to degrade via hydrolysis after at least one of a predetermined time or an environmental condition. The scaffold is configured to be applied to the tissue substrate containing the defect, and is sufficiently flexible to facilitate application of the scaffold to uneven surfaces of the tissue substrate, and to enable movement of the scaffold by the tissue substrate.

A multi-laminar electrospun nanofiber scaffold for use in repairing a defect in a tissue substrate is provided. The scaffold includes a first layer formed by a first plurality of electrospun polymeric fibers, and a second layer formed by a second plurality of electrospun polymeric fibers. The second layer is combined with the first layer. A first portion of the scaffold includes a higher density of fibers than a second portion of the scaffold, and the first portion has a higher tensile strength than the second portion. The scaffold is configured to degrade via hydrolysis after at least one of a predetermined time or an environmental condition. The scaffold is configured to be applied to the tissue substrate containing the defect, and is sufficiently flexible to facilitate application of the scaffold to uneven surfaces of the tissue substrate, and to enable movement of the scaffold by the tissue substrate.

A method of making nonwoven webs comprising providing a spinneret including a pattern of conduits forming an extrusion region; directing only a first stream of molten propylene polymer into a region adjacent the first side of the spinneret, directing only a second stream of molten propylene polymer into a region distal to the first side of the spinneret, extruding only the first stream propylene polymer through the exit openings in a first zone where the exit opening comprises exit ports in the first zone having a first density; extruding only the second stream propylene polymer through the exit openings of a second zone where the exit opening comprises exit ports in the second zone having a second density less than the first density; and the second zone is distal to the first side with the first zone being between the second zone and the first side.

A method of making nonwoven webs comprising providing a spinneret including a pattern of conduits forming an extrusion region; directing only a first stream of molten propylene polymer into a region adjacent the first side of the spinneret, directing only a second stream of molten propylene polymer into a region distal to the first side of the spinneret, extruding only the first stream propylene polymer through the exit openings in a first zone where the exit opening comprises exit ports in the first zone having a first density; extruding only the second stream propylene polymer through the exit openings of a second zone where the exit opening comprises exit ports in the second zone having a second density less than the first density; and the second zone is distal to the first side with the first zone being between the second zone and the first side.

A nonwoven fabric layered body includes, in the following order, a crimped surface layer including a crimped spunbond nonwoven fabric including a crimped fiber, a crimped intermediate layer including a crimped spunbond nonwoven fabric including a crimped fiber, and a non-crimped surface layer including a non-crimped spunbond nonwoven fabric including a non-crimped fiber, a linear mass density of the crimped fiber in the crimped surface layer is from 1.4 denier to 1.6 denier, and a linear mass density of the crimped fiber in the crimped intermediate layer is less than 1.4 denier.

A nonwoven fabric layered body includes, in the following order, a crimped surface layer including a crimped spunbond nonwoven fabric including a crimped fiber, a crimped intermediate layer including a crimped spunbond nonwoven fabric including a crimped fiber, and a non-crimped surface layer including a non-crimped spunbond nonwoven fabric including a non-crimped fiber, a linear mass density of the crimped fiber in the crimped surface layer is from 1.4 denier to 1.6 denier, and a linear mass density of the crimped fiber in the crimped intermediate layer is less than 1.4 denier.

A napped artificial leather includes: a non-woven fabric that is art entangled body of ultrafine fibers, and an elastic polymer applied into the non-woven fabric; where the napped artificial leather has, on at least one side thereof, a napped surface formed by napping the ultrafine fibers. Each of the ultrafine fibers is art ultrafine fiber having a fineness of 0.5 dtex or less, and a tensile strength of 6 to 9 mN. A plurality of the ultrafine fibers form a fiber bundle, and the ultrafine fibers that form the fiber bundle are not constrained by the elastic polymer in a region of the napped artificial leather other than a surface layer portion. A content ratio of the elastic polymer is 16 to 40 mass %, and the napped artificial leather has an apparent density of 0.38 g/cm.sup.3 or more.

Nonwoven multilayer structures having at least two nanofiber layers are described herein. The nonwoven multilayer structure may have two nanofibers layers that have different properties from each other, such as fiber diameter. One nanofiber layer may be produced by an electrospinning process, while another nanofiber layer may be produced by a melt blown process.