Filamentary structure

Claim 2

A filamentary structure characterised in that it has a helical thermoplastic core filament (6, 12) disposed within a thermoplastic sheath component (7, 13) which is fused to the successive turns (8, 14) of the helical core filament.

Claim 3

A filamentary structure as claimed in claim 1 characterised in that the sheath component comprises a cage formed by at least three thermoplastic filaments (7) each of which is fused to the successive turns (8) of the helical core filament.

Claim 4

A filamentary structure as claimed in claim 2 characterised in that each cage filament (7) is spaced apart from its adjacent cage filaments by substantially equal distances.

Claim 5

A filamentary structure as claimed in claim 2 or claim 3 characterised in that the cage filaments (7) are in substantially parallel alignment with the axis of the helical core filament (6).

Claim 6

A filamentary structure as claimed in any of claims 2 to 4 characterised in that each of the cage filaments (7) is of smaller cross-sectional area than the helical core filament (6).

Claim 7

A filamentary structure as claimed in claim 1 characterised in that the sheath component comprises a tube (13).

Claim 8

A filamentary structure as claimed in any of claims 1 to 6 characterised in that the helical core filament (6, 12) and the sheath component (7, 13) comprise the same thermoplastic polymer.

Claim 9

A fabric structure characterised by a plurality of filamentary structures as claimed in any of claims 1 to 7 fused to each other with the axes of the helical filaments (22, 23) in substantially parallel relation.

Claim 10

A fabric structure as claimed in claim 8 characterised in that the component filamentary structures are arranged in a planar array.

Claim 11

A process for making a filamentary structure characterised by feeding molten thermoplastic polymer to a spinning jet (1) having an inner jet hole (3, 16) ringed by outer jet holes (4, 17), extruding the polymer through the inner jet hole (3) at a greater velocity than polymer is extruded through the outer jet holes (4) to form a helical extrudate disposed within an extruded sheath component to which its successive turns are fused, and cooling the extrudates to solidify them to a unitary structure.

Claim 12

A process for making a filamentary structure characterised by feeding molten thermoplastic polymer to a spinning jet (1) having an inner jet hole (3, 16) ringed by outer jet holes (4, 17), extruding the polymer through the inner jet hole (3) at a greater velocity than polymer is extruded through the outer jet holes (4) to form a helical extrudate disposed within an extruded sheath component to which its successive turns are fused, and cooling the extrudates to solidify them to a unitary structure.

Claim 13

A process as claimed in claim 10 characterised in that each outer jet hole (4) is positioned sufficiently closely to its adjacent outer jet holes (4) that the extrudates from the outer jet holes merge to form a tubular sheath component.

Claim 14

A process as claimed in claim 10 or 11 characterised in that each of the outer jet holes (4) of the spinning jet is of smaller cross-sectional area than the inner jet hole (3).

Claim 15

A process as claimed in any of claims 10 to 12 characterised in that the filamentary structure produced is stretched and then allowed to relax to cause the cage filaments (19) which comprise the sheath component to balloon out between the points where they are fused to the helical core filament (18) and thereby give an expanded structure (20).

Claim 16

A process as claimed in any of claims 10 to 12 characterised in that the filamentary structure (5) produced is stretched to the extent that the cage filaments (7) which comprise the sheath component break between the points (8) where they are fused to the helical core filament (6) to produce a modified filamentary structure in which the broken cage filaments constitute fibrils (10) which are substantially uniform in length with the majority being raked in a common direction.

Claim 17

A process for making a fabric structure by a process as claimed in any of claims 10 to 14 characterised in that a plurality of filamentary structures are extruded adjacent to each other with the axes of the helical core filaments substantially parallel whereby the extruded filamentary structures fuse to each other and after being cooled to solidify them remain fused as a unitary fabric structure.

Claim 18

A process as claimed in claim 15 characterised in that the filamentary structures are extruded as a planar array and become fused to each other in the form of a planar fabric.