Filament networks and methods of making same for use in the manufacture of products with enhanced characteristics

Abstract

The present invention relates to the production of filament networks that can serve as intermediates for the production of goods to impart enhanced performance characteristics such as strength and flame resistance. This filament network intermediate includes a plurality of filaments of one or more types of materials, wherein the filaments are randomly associated in the network in a wool-like configuration. The present invention also relates to a two-step process for making filament networks that may be performed by a single apparatus. The present invention further relates to an apparatus for feeding and drafting fibers to produce filament networks.

Description

TECHNICAL FIELD [0001] The present invention relates to the production of filament networks that can serve as intermediates for the production of goods to impart enhanced performance characteristics such as strength and flame resistance. This filament network intermediate includes a plurality of filaments of one or more types of materials, wherein the filaments are randomly associated in the network in a wool-like configuration. The present invention also relates to a two-step process for making filament networks that may be performed by a single apparatus. The present invention further relates to an apparatus for feeding and drafting fibers to produce filament networks. BACKGROUND OF THE INVENTION [0002] Carbon fibers are long bundles of linked graphite plates that form a crystal structure laying parallel to the axis of the fiber. Like all crystalline structures, they are anisotropic. Their elastic modulus is higher in the direction of the axis than it is against the axis. In other...

AI Technical Summary

Benefits of technology

[0009] In accordance with the present invention, a filament network intermediate includes a plurality of wool-like filaments with a length of no greater than 40 cm. The filament network is obtained from a variety of fibers, including oxidized PAN fibers, stainless steel fibers, aramid fibers, and polyester fibers. Unlike their precursor fibers, which generally have long and well aligned filaments, the filament networks produced are wool-like filament networks which contain a plurality of short wavy filaments randomly piled together and the filaments are held together by mechanical, physical and noncovalent chemical forces. In one aspect, oxidized PAN filament networks are produced from long and aligned oxidized PAN fibers. The filaments of the networks have a length of no greater than 22 cm and a width of no greater than about 12 micrometers. In another aspect, a stainless steel filament network is produced from an aligned and long stainless steel fiber. The filaments of the network product have a length of no greater than about 10 cm and a width of no greater than about 8 micrometers. In yet another aspect, the aramid filament network is produced from an aligned and long aramid fiber. The filaments of the network product have a length of no greater than about 22 cm and a width of no greater than about 12 micrometers.

[0010] In another embodiment of the present invention, an apparatus for producing a filament network includes a feeding component and a drafting component. The feeding component delivers one or more types of fibers to the drafting component. In one aspect, the drafting component comprises two pairs of rollers and a pressurizing element, such as a weight element. The weight element can be adjusted to exert appropriate pressure on each pair of rollers so that the fiber can only be moved by the rotation of the rollers. The drafting of a fiber is accomplished by the force created by the two pairs of rollers, wherein the first rollers rotate slower than the last rollers. This causes the fiber to be both stretched and broken between the two pairs of rollers. In another aspect, the drafting component further comprises one or more intermediate pairs of rollers. The intermediate pairs are so arranged that the fiber to be drafted contacts first with the first rollers, then with the intermediate rollers, and then with the last rollers to exit the drafting component to form a wool-like filament network. Preferably, the apparatus comprises one intermediate pair of rollers. In yet another aspect, the apparatus of the present invention may further comprise a twisting and winding component, wherein the filament network formed during the feeding and drafting components is spun into yarn.

[0011] In yet another embodiment of the present invention, a method of forming a fluffy and randomized filament network intermediate product from an aligned and long fiber includes feeding and drafting steps. One or more types of fibers are first delivered simultaneously from the feeding component to the drafting component with minimum twisting. The fibers are then drafted to produce the filament network intermediate. This intermediate can be further processed into fine spun yarns on the same apparatus, or it can be used in the manufacture of nonwoven products.

Problems solved by technology

Pitch-based carbon fiber has much greater stiffness, but it is brittle and costly to produce.

In addition, they have excellent heat insulation properties, which are derived from the heat stabilized PAN chemistry and resultant low thermal conductivity.

Furthermore, the oxidized fibers are electrically non-conductive and function as effective electrical insulator even after exposure to heat and open flames.

These processes are laborious, inefficient and costly, and often require more than one type of apparatus to perform.

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