Patent ES-344782-A1 (ES)
Title: Textile Fabric of Multifilament Yarns and a Process and Apparatus for the Manufacture of such Yarns.
IPC: D01D5/30
Filed: 1967-09-06
Abstract: A multi-filament yarn is derived from synthetic, thermoplastic polymers, each filament being composed of two different polymers which are intermingled in the form of a plurality of continuous core fibrils embedded in a matrix, the first of said polymers when in the solidified state having a dimensional stability when it is loaded less dependent on temperature than the other polymer and said first polymer being present in a matrix of the other polymer in the form of at least 100 continuous core fibrils per yarn filament, which fibrils have cross-sectional dimensions of the same order of magnitude in all directions, and the core fibrils together constituting 20 to 50% of the weight of the filaments. Preferably, the core fibrils measure less than 4 microns in cross-section, and especially less than 1 micron, and are so distributed within the filaments that they are spaced at substantially equal distances from one another. The preferred copolymer is polyethylene terephthalate having a relative viscosity of at least 1À5 determined at 25 C. on a 1% solution of the polymer in meta-cresol, and the preferred matrix polymer is a polyamide, especially polyhexamethylene adipamide having a relative viscosity of at least 2À3 determined at 25 C. on a 1% solution of the polymer in 90% by weight formic acid. In a preferred embodiment, each filament is provided with an annular zone extending along its periphery, said zone being substantially free from core fibrils, and extending radially inward from the periphery of the filaments to a distance desirably from 5 to 10% of the radius of the filaments. Such multifilament yarns may be made by a process comprising forming a multilayer stream of two synthetic thermoplastic polymers, the first of said polymers when in the solidified state having a dimensional stability when it is loaded less dependent on temperature than the other polymer, and before it is distributed over the spinning orifices and while the same direction of flow is maintained, causing the multilayer stream to split up at least once in a direction transverse to that of the layers into substreams so that at least 100 substreams of said first polymer are formed, having transverse dimensions of the order of magnitude of the layer thickness in situ, and the substreams together constituting 20 to 50% of the weight of the filamentary stream, and while maintaining the same direction of flow subsequently feeding the multilayer stream to the spinning orifices in a spinneret plate. Apparatus as shown comprises two feed systems for spinning liquids, said systems ending in a mixing apparatus of the type capable of forming the spinning liquids into a multilayered stream a spinneret plate provided with spinning orifices, downstream of said mixing apparatus and before the spinneret plate at least one gauze screen having a mesh width of approximately 2 x n, where n represents the thickness of the layers of the polymeric core material at the gauze or gauzes. Preferably, the mixing device is of the type which forms flat layers. Thus in Fig. 1, two different spinning liquids may be sucked through feed conduits 3 and 4 into pumps 1 and 2 and subsequently be pumped into conduits 5 and 6 which contain filters (not shown) which are finer than those of gauzes 11. Conduits 5 and 6 symmetrically end in a conduit 7 through which the two spinning liquids flow downwardly side by side. Conduit 7 comprises a widened section 9 in which there is provided a mixer (not shown) in which the number of layers of the two spinning liquids is repeatedly doubled from two to over a thousand. After the mixer, conduit 7 remains rectangular in cross-section but diverges in the downward direction, and ends in spinning assembly 8 in which there is placed a 140-orifice spinneret plate 10, positioned over which is a combination of various gauzes 11 of the following mesh sizes per linear inch: 1 gauze of 60 mesh, 2 gauzes each of 325 mesh, and 1 gauze of 60 mesh. Fig. 2 (not shown) represents a crosssection of the layer stream of the spinning liquid as it arrives at the combination of gauzes at the line II-II in Fig. 1. Fig. 3 (not shown) shows the pattern of this layered stream after it has passed the combination of gauzes 11, and Fig. 4 shows the cross-section of the spinning liquid just prior to entering the orifices of the spinneret. Yarn so made may be suitably dyed with a dyestuff capable of dyeing the two component polymers, and may be made into tyre cord and textile fabric by known methods.