GB1179615A - Producing Conjugate Filaments by Melt Extrusion - Google Patents

Abstract

1,179,615. Melt spinning conjugate filaments. IMPERIAL CHEMICAL INDUSTRIES Ltd. 28 Nov., 1968 [5 Dec., 1967], No. 55311/67. Heading B5B. Conjugate filaments (which may be of the " side-by-side " or of the " sheath-core " type) are made by a process wherein the conjugate components result from the splitting of a single stream of a molten, fibre-forming polymer into individually metered sub-streams, modifying at least one of the sub-streams by incorporation into it of a metered proportion of a compound in the liquid state, said compound being capable under the conditions of melt extrusion of altering the melt viscosity of the polymer by reaction with it, thereafter bringing together the separate sub-streams to form at least one conjugate stream, and converting the conjugate stream or streams into conjugate filaments. The fibre-forming polymer may be a polyester and the liquid metered into one of the substreams of molten polyester may be a reactant capable under the conditions of melt extrusion of lowering the molecular weight and therefore the melt viscosity of the polyester. The polyester may be poly (ethylene terephthalate). The conversion of the conjugate stream into conjugate filaments may be effected by feeding the stream to a multi-hole spinneret adapted for the spinning of conjugate filaments or by feeding the stream to a straight or annular extrusion slot with production of a conjugate film which is thereafter slit to form conjugate filaments. The reactant used when the fibre-forming polymer is a polyester may be a glycol, a polyglycol, bis- #-hydroxy alkyl terephthalate, or an oligomer, which may be that of the polyester or of a second polyester. The reactant should preferably have a molecular weight of at least 500. When the filaments to be produced are crimped filaments the difference between the intrinsic viscosities of the polyesters in the two streams should be at least 0À05 units of intrinsic viscosity, this viscosity being defined as limit where C is concentration in grams per decilitre, # is the viscosity of the solution of the polymer and # 0 is the viscosity of the pure solvent, viscosity determinations being carried out in orthochlorophenol solution at 25‹ C. The normal melt-spinning temperature is about 280- 300‹ C. Conjugate filaments may be produced in which crimp is developed merely on subjecting them to the normal drawing stage or in which the crimp is enhanced or wholly developed during a heat treatment subsequent to the drawing stage.