The invention is a nonwoven fabric characterized by satisfying 0.25≤(L.sup.2/V)≤10, when an average fiber diameter of all fibers is L (μm) and a volume per m.sup.2 is V (cm.sup.3). The nonwoven fabric leads to a solid electrolyte-carrying sheet in which solid electrolyte particles are carried between fibers and which can achieve a good balance among thickness reduction, powder falling property of the solid electrolyte particles, and electrical conductivity.

An article of apparel including insulation material includes an insulating layer formed of waterfowl fibers and synthetic fibers. The waterfowl fibers can be present in an amount of at least 20% by weight of the insulating layer. The insulating layer is generally free of waterfowl plumage.

The problem to be solved by the present invention is to provide a polyester binder fiber having a low crystallization temperature and exhibiting improved adhesiveness and a fiber structure including the polyester binder fiber. The polyester binder fiber according to the present invention includes a polyester polymer and an amorphous polyether imide polymer in a proportion of 0.1 to 5.0 mass % (based on the mass of the polyester polymer), and the polyester binder fiber has a crystallization temperature measured by differential calorimetry in a range of 100° C. or higher and 250° C. or lower.

The problem to be solved by the present invention is to provide a polyester binder fiber having a low crystallization temperature and exhibiting improved adhesiveness and a fiber structure including the polyester binder fiber. The polyester binder fiber according to the present invention includes a polyester polymer and an amorphous polyether imide polymer in a proportion of 0.1 to 5.0 mass % (based on the mass of the polyester polymer), and the polyester binder fiber has a crystallization temperature measured by differential calorimetry in a range of 100° C. or higher and 250° C. or lower.

An external material for vehicles may include a non-woven fabric having a honeycomb structure and a wheel guard including the same.

A method may produce a heat-resistant resin composite excellent in heat resistance and bending properties. This heat-resistant resin composite is constituted of a matrix resin and reinforcing fibers dispersed in the matrix resin. The matrix resin is constituted of a heat-resistant thermoplastic polymer having a glass transition temperature of 100° C. or higher, and a polyester-based polymer comprising a terephthalic acid unit (A) and an isophthalic acid unit (B) at a copolymerization proportion (molar ratio) of (A)/(B)=100/0 to 40/60. The proportion of the heat-resistant thermoplastic polymer in the composite is 30 to 80 wt %.

A method may produce a heat-resistant resin composite excellent in heat resistance and bending properties. This heat-resistant resin composite is constituted of a matrix resin and reinforcing fibers dispersed in the matrix resin. The matrix resin is constituted of a heat-resistant thermoplastic polymer having a glass transition temperature of 100° C. or higher, and a polyester-based polymer comprising a terephthalic acid unit (A) and an isophthalic acid unit (B) at a copolymerization proportion (molar ratio) of (A)/(B)=100/0 to 40/60. The proportion of the heat-resistant thermoplastic polymer in the composite is 30 to 80 wt %.

A non-woven fabric base material for a lithium ion secondary battery separator composed mainly of a polyethylene terephthalate fiber, characterized in that the non-woven fabric base material comprises a polyethylene terephthalate binder fiber and a crystallized polyethylene terephthalate fiber, and the content of a polyethylene terephthalate binder fiber having a fiber length of 2.5 mm or less is 10 to 60 mass %.

A non-woven fabric base material for a lithium ion secondary battery separator composed mainly of a polyethylene terephthalate fiber, characterized in that the non-woven fabric base material comprises a polyethylene terephthalate binder fiber and a crystallized polyethylene terephthalate fiber, and the content of a polyethylene terephthalate binder fiber having a fiber length of 2.5 mm or less is 10 to 60 mass %.

A nonwoven fabric and a method of making thereof. The nonwoven fabric includes a plurality of randomly-oriented fibers, the plurality of randomly-oriented fibers including: at least 60 wt % of oxidized polyacrylonitrile fibers; and from to less than 40 wt % of reinforcing fibers having an outer surface comprised of a (co)polymer with a melting temperature of from 100° C. to 450° C.; and a fluoropolymer binder on the plurality of randomly-oriented fibers; wherein the plurality of randomly-oriented fibers is bonded together to form the nonwoven fabric, optionally wherein the nonwoven fabric has a thickness of one millimeter or less.