A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.

A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.

A rigid nylon porous material sheet is produced by the adhesive bonding of kinked nylon fibers having lengths of 1 to 5 inches. These fibers are cut from melt spun nylon or harvested from clean carpet fibers by shearing. The adhesive used is glycol, which attacks nylon at 180 C. forming a gel on the surface of the kinked fibers, but does not attack the nylon fibers when the kinked fiber assembly is cooled to 150 C. to precipitate ultrafine nylon within the gel. The fiber assembly is heated to 160 C. to bond the nylon fibers. It is then washed in hot water to remove unused glycol. The other adhesive is polyurethane, which is applied to the kinked fibers using coupling agents of aqueous resorcinol and vinyl pyrrolidone.

According to one embodiment, a fiber sheet includes a plurality of fibers. The plurality of fibers are in a closely-adhered state.

All of the following (1) to (3) are satisfied, where F1 is a tensile strength in a first direction, and F2 is a tensile strength in a second direction orthogonal to the first direction: (1) F2>F1; (2) F1 is 1 MPa or more; and (3) F2/F1 is 2 or more.

According to one embodiment, a fiber sheet includes a plurality of fibers. The plurality of fibers are in a closely-adhered state.

All of the following (1) to (3) are satisfied, where F1 is a tensile strength in a first direction, and F2 is a tensile strength in a second direction orthogonal to the first direction: (1) F2>F1; (2) F1 is 1 MPa or more; and (3) F2/F1 is 2 or more.

A moldable composite sheet having improved thermal and mechanical property characteristics. In one aspect, the composite sheet may be a porous fiber-reinforced thermoplastic resin comprising discontinuous mineral reinforcing fibers, and one or more skin layer materials. Generally, the composite sheet may have a void content or porosity from about 5% to about 95% by volume of the sheet, an areal weight between about 400 g/m.sup.2 to about 4000 g/m.sup.2 (gsm), a mineral fiber content from about 20% to about 80% by weight, and a thermoplastic resin content from about 20% to about 80% by weight of the composite sheet. The composite sheet can be molded via low pressure processes, such as thermoforming, match metal molding on stops, vacuum forming and pressure forming, to produce durable automotive interior trim parts and construction articles having improved thermal and mechanical properties in addition to other beneficial characteristics.

A moldable composite sheet having improved thermal and mechanical property characteristics. In one aspect, the composite sheet may be a porous fiber-reinforced thermoplastic resin comprising discontinuous mineral reinforcing fibers, and one or more skin layer materials. Generally, the composite sheet may have a void content or porosity from about 5% to about 95% by volume of the sheet, an areal weight between about 400 g/m.sup.2 to about 4000 g/m.sup.2 (gsm), a mineral fiber content from about 20% to about 80% by weight, and a thermoplastic resin content from about 20% to about 80% by weight of the composite sheet. The composite sheet can be molded via low pressure processes, such as thermoforming, match metal molding on stops, vacuum forming and pressure forming, to produce durable automotive interior trim parts and construction articles having improved thermal and mechanical properties in addition to other beneficial characteristics.

In a method for producing a filter medium, at least one substrate layer of a nonwoven comprising cellulose fibers and/or synthetic polymer fibers is provided and a fiber layer of polymer fibers is deposited on the at least one substrate layer. Prior to depositing the fiber layer, a solvent is applied to the at least one substrate layer, wherein a material of the substrate layer and/or a material of the fiber layer is soluble in the solvent. A filter medium produced by the method has material-fused connections at crossing points of the polymer fibers and/or cellulose fibers of the substrate layer with the polymer fibers of the fiber layer.

In a method for producing a filter medium, at least one substrate layer of a nonwoven comprising cellulose fibers and/or synthetic polymer fibers is provided and a fiber layer of polymer fibers is deposited on the at least one substrate layer. Prior to depositing the fiber layer, a solvent is applied to the at least one substrate layer, wherein a material of the substrate layer and/or a material of the fiber layer is soluble in the solvent. A filter medium produced by the method has material-fused connections at crossing points of the polymer fibers and/or cellulose fibers of the substrate layer with the polymer fibers of the fiber layer.

According to one embodiment, a fiber sheet includes a plurality of fibers. The plurality of fibers are in a closely-adhered state. All of the following (1) to (3) are satisfied, where F1 is a tensile strength in a first direction, and F2 is a tensile strength in a second direction orthogonal to the first direction: (1) F2>F1; (2) F1 is 1 MPa or more; and (3) F2/F1 is 2 or more.